;(function (f) {
  if (typeof exports === 'object' && typeof module !== 'undefined') {
    module.exports = f()
  } else if (typeof define === 'function' && define.amd) {
    define([], f)
  } else {
    var g
    if (typeof window !== 'undefined') {
      g = window
    } else if (typeof global !== 'undefined') {
      g = global
    } else if (typeof self !== 'undefined') {
      g = self
    } else {
      g = this
    }
    g.chai = f()
  }
})(function () {
  var define, module, exports
  return (function () {
    function r(e, n, t) {
      function o(i, f) {
        if (!n[i]) {
          if (!e[i]) {
            var c = 'function' == typeof require && require
            if (!f && c) return c(i, !0)
            if (u) return u(i, !0)
            var a = new Error("Cannot find module '" + i + "'")
            throw ((a.code = 'MODULE_NOT_FOUND'), a)
          }
          var p = (n[i] = { exports: {} })
          e[i][0].call(
            p.exports,
            function (r) {
              var n = e[i][1][r]
              return o(n || r)
            },
            p,
            p.exports,
            r,
            e,
            n,
            t
          )
        }
        return n[i].exports
      }
      for (
        var u = 'function' == typeof require && require, i = 0;
        i < t.length;
        i++
      )
        o(t[i])
      return o
    }
    return r
  })()(
    {
      1: [
        function (require, module, exports) {
          module.exports = require('./lib/chai')
        },
        { './lib/chai': 2 }
      ],
      2: [
        function (require, module, exports) {
          /*!
           * chai
           * Copyright(c) 2011-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          var used = []

          /*!
           * Chai version
           */

          exports.version = '4.3.3'

          /*!
           * Assertion Error
           */

          exports.AssertionError = require('assertion-error')

          /*!
           * Utils for plugins (not exported)
           */

          var util = require('./chai/utils')

          /**
           * # .use(function)
           *
           * Provides a way to extend the internals of Chai.
           *
           * @param {Function}
           * @returns {this} for chaining
           * @api public
           */

          exports.use = function (fn) {
            if (!~used.indexOf(fn)) {
              fn(exports, util)
              used.push(fn)
            }

            return exports
          }

          /*!
           * Utility Functions
           */

          exports.util = util

          /*!
           * Configuration
           */

          var config = require('./chai/config')
          exports.config = config

          /*!
           * Primary `Assertion` prototype
           */

          var assertion = require('./chai/assertion')
          exports.use(assertion)

          /*!
           * Core Assertions
           */

          var core = require('./chai/core/assertions')
          exports.use(core)

          /*!
           * Expect interface
           */

          var expect = require('./chai/interface/expect')
          exports.use(expect)

          /*!
           * Should interface
           */

          var should = require('./chai/interface/should')
          exports.use(should)

          /*!
           * Assert interface
           */

          var assert = require('./chai/interface/assert')
          exports.use(assert)
        },
        {
          './chai/assertion': 3,
          './chai/config': 4,
          './chai/core/assertions': 5,
          './chai/interface/assert': 6,
          './chai/interface/expect': 7,
          './chai/interface/should': 8,
          './chai/utils': 23,
          'assertion-error': 34
        }
      ],
      3: [
        function (require, module, exports) {
          /*!
           * chai
           * http://chaijs.com
           * Copyright(c) 2011-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          var config = require('./config')

          module.exports = function (_chai, util) {
            /*!
             * Module dependencies.
             */

            var AssertionError = _chai.AssertionError,
              flag = util.flag

            /*!
             * Module export.
             */

            _chai.Assertion = Assertion

            /*!
             * Assertion Constructor
             *
             * Creates object for chaining.
             *
             * `Assertion` objects contain metadata in the form of flags. Three flags can
             * be assigned during instantiation by passing arguments to this constructor:
             *
             * - `object`: This flag contains the target of the assertion. For example, in
             *   the assertion `expect(numKittens).to.equal(7);`, the `object` flag will
             *   contain `numKittens` so that the `equal` assertion can reference it when
             *   needed.
             *
             * - `message`: This flag contains an optional custom error message to be
             *   prepended to the error message that's generated by the assertion when it
             *   fails.
             *
             * - `ssfi`: This flag stands for "start stack function indicator". It
             *   contains a function reference that serves as the starting point for
             *   removing frames from the stack trace of the error that's created by the
             *   assertion when it fails. The goal is to provide a cleaner stack trace to
             *   end users by removing Chai's internal functions. Note that it only works
             *   in environments that support `Error.captureStackTrace`, and only when
             *   `Chai.config.includeStack` hasn't been set to `false`.
             *
             * - `lockSsfi`: This flag controls whether or not the given `ssfi` flag
             *   should retain its current value, even as assertions are chained off of
             *   this object. This is usually set to `true` when creating a new assertion
             *   from within another assertion. It's also temporarily set to `true` before
             *   an overwritten assertion gets called by the overwriting assertion.
             *
             * @param {Mixed} obj target of the assertion
             * @param {String} msg (optional) custom error message
             * @param {Function} ssfi (optional) starting point for removing stack frames
             * @param {Boolean} lockSsfi (optional) whether or not the ssfi flag is locked
             * @api private
             */

            function Assertion(obj, msg, ssfi, lockSsfi) {
              flag(this, 'ssfi', ssfi || Assertion)
              flag(this, 'lockSsfi', lockSsfi)
              flag(this, 'object', obj)
              flag(this, 'message', msg)

              return util.proxify(this)
            }

            Object.defineProperty(Assertion, 'includeStack', {
              get: function () {
                console.warn(
                  'Assertion.includeStack is deprecated, use chai.config.includeStack instead.'
                )
                return config.includeStack
              },
              set: function (value) {
                console.warn(
                  'Assertion.includeStack is deprecated, use chai.config.includeStack instead.'
                )
                config.includeStack = value
              }
            })

            Object.defineProperty(Assertion, 'showDiff', {
              get: function () {
                console.warn(
                  'Assertion.showDiff is deprecated, use chai.config.showDiff instead.'
                )
                return config.showDiff
              },
              set: function (value) {
                console.warn(
                  'Assertion.showDiff is deprecated, use chai.config.showDiff instead.'
                )
                config.showDiff = value
              }
            })

            Assertion.addProperty = function (name, fn) {
              util.addProperty(this.prototype, name, fn)
            }

            Assertion.addMethod = function (name, fn) {
              util.addMethod(this.prototype, name, fn)
            }

            Assertion.addChainableMethod = function (
              name,
              fn,
              chainingBehavior
            ) {
              util.addChainableMethod(
                this.prototype,
                name,
                fn,
                chainingBehavior
              )
            }

            Assertion.overwriteProperty = function (name, fn) {
              util.overwriteProperty(this.prototype, name, fn)
            }

            Assertion.overwriteMethod = function (name, fn) {
              util.overwriteMethod(this.prototype, name, fn)
            }

            Assertion.overwriteChainableMethod = function (
              name,
              fn,
              chainingBehavior
            ) {
              util.overwriteChainableMethod(
                this.prototype,
                name,
                fn,
                chainingBehavior
              )
            }

            /**
             * ### .assert(expression, message, negateMessage, expected, actual, showDiff)
             *
             * Executes an expression and check expectations. Throws AssertionError for reporting if test doesn't pass.
             *
             * @name assert
             * @param {Philosophical} expression to be tested
             * @param {String|Function} message or function that returns message to display if expression fails
             * @param {String|Function} negatedMessage or function that returns negatedMessage to display if negated expression fails
             * @param {Mixed} expected value (remember to check for negation)
             * @param {Mixed} actual (optional) will default to `this.obj`
             * @param {Boolean} showDiff (optional) when set to `true`, assert will display a diff in addition to the message if expression fails
             * @api private
             */

            Assertion.prototype.assert = function (
              expr,
              msg,
              negateMsg,
              expected,
              _actual,
              showDiff
            ) {
              var ok = util.test(this, arguments)
              if (false !== showDiff) showDiff = true
              if (undefined === expected && undefined === _actual)
                showDiff = false
              if (true !== config.showDiff) showDiff = false

              if (!ok) {
                msg = util.getMessage(this, arguments)
                var actual = util.getActual(this, arguments)
                var assertionErrorObjectProperties = {
                  actual: actual,
                  expected: expected,
                  showDiff: showDiff
                }

                var operator = util.getOperator(this, arguments)
                if (operator) {
                  assertionErrorObjectProperties.operator = operator
                }

                throw new AssertionError(
                  msg,
                  assertionErrorObjectProperties,
                  config.includeStack ? this.assert : flag(this, 'ssfi')
                )
              }
            }

            /*!
             * ### ._obj
             *
             * Quick reference to stored `actual` value for plugin developers.
             *
             * @api private
             */

            Object.defineProperty(Assertion.prototype, '_obj', {
              get: function () {
                return flag(this, 'object')
              },
              set: function (val) {
                flag(this, 'object', val)
              }
            })
          }
        },
        { './config': 4 }
      ],
      4: [
        function (require, module, exports) {
          module.exports = {
            /**
             * ### config.includeStack
             *
             * User configurable property, influences whether stack trace
             * is included in Assertion error message. Default of false
             * suppresses stack trace in the error message.
             *
             *     chai.config.includeStack = true;  // enable stack on error
             *
             * @param {Boolean}
             * @api public
             */

            includeStack: false,

            /**
             * ### config.showDiff
             *
             * User configurable property, influences whether or not
             * the `showDiff` flag should be included in the thrown
             * AssertionErrors. `false` will always be `false`; `true`
             * will be true when the assertion has requested a diff
             * be shown.
             *
             * @param {Boolean}
             * @api public
             */

            showDiff: true,

            /**
             * ### config.truncateThreshold
             *
             * User configurable property, sets length threshold for actual and
             * expected values in assertion errors. If this threshold is exceeded, for
             * example for large data structures, the value is replaced with something
             * like `[ Array(3) ]` or `{ Object (prop1, prop2) }`.
             *
             * Set it to zero if you want to disable truncating altogether.
             *
             * This is especially userful when doing assertions on arrays: having this
             * set to a reasonable large value makes the failure messages readily
             * inspectable.
             *
             *     chai.config.truncateThreshold = 0;  // disable truncating
             *
             * @param {Number}
             * @api public
             */

            truncateThreshold: 40,

            /**
             * ### config.useProxy
             *
             * User configurable property, defines if chai will use a Proxy to throw
             * an error when a non-existent property is read, which protects users
             * from typos when using property-based assertions.
             *
             * Set it to false if you want to disable this feature.
             *
             *     chai.config.useProxy = false;  // disable use of Proxy
             *
             * This feature is automatically disabled regardless of this config value
             * in environments that don't support proxies.
             *
             * @param {Boolean}
             * @api public
             */

            useProxy: true,

            /**
             * ### config.proxyExcludedKeys
             *
             * User configurable property, defines which properties should be ignored
             * instead of throwing an error if they do not exist on the assertion.
             * This is only applied if the environment Chai is running in supports proxies and
             * if the `useProxy` configuration setting is enabled.
             * By default, `then` and `inspect` will not throw an error if they do not exist on the
             * assertion object because the `.inspect` property is read by `util.inspect` (for example, when
             * using `console.log` on the assertion object) and `.then` is necessary for promise type-checking.
             *
             *     // By default these keys will not throw an error if they do not exist on the assertion object
             *     chai.config.proxyExcludedKeys = ['then', 'inspect'];
             *
             * @param {Array}
             * @api public
             */

            proxyExcludedKeys: ['then', 'catch', 'inspect', 'toJSON']
          }
        },
        {}
      ],
      5: [
        function (require, module, exports) {
          /*!
           * chai
           * http://chaijs.com
           * Copyright(c) 2011-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          module.exports = function (chai, _) {
            var Assertion = chai.Assertion,
              AssertionError = chai.AssertionError,
              flag = _.flag

            /**
             * ### Language Chains
             *
             * The following are provided as chainable getters to improve the readability
             * of your assertions.
             *
             * **Chains**
             *
             * - to
             * - be
             * - been
             * - is
             * - that
             * - which
             * - and
             * - has
             * - have
             * - with
             * - at
             * - of
             * - same
             * - but
             * - does
             * - still
             * - also
             *
             * @name language chains
             * @namespace BDD
             * @api public
             */

            ;[
              'to',
              'be',
              'been',
              'is',
              'and',
              'has',
              'have',
              'with',
              'that',
              'which',
              'at',
              'of',
              'same',
              'but',
              'does',
              'still',
              'also'
            ].forEach(function (chain) {
              Assertion.addProperty(chain)
            })

            /**
             * ### .not
             *
             * Negates all assertions that follow in the chain.
             *
             *     expect(function () {}).to.not.throw();
             *     expect({a: 1}).to.not.have.property('b');
             *     expect([1, 2]).to.be.an('array').that.does.not.include(3);
             *
             * Just because you can negate any assertion with `.not` doesn't mean you
             * should. With great power comes great responsibility. It's often best to
             * assert that the one expected output was produced, rather than asserting
             * that one of countless unexpected outputs wasn't produced. See individual
             * assertions for specific guidance.
             *
             *     expect(2).to.equal(2); // Recommended
             *     expect(2).to.not.equal(1); // Not recommended
             *
             * @name not
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('not', function () {
              flag(this, 'negate', true)
            })

            /**
             * ### .deep
             *
             * Causes all `.equal`, `.include`, `.members`, `.keys`, and `.property`
             * assertions that follow in the chain to use deep equality instead of strict
             * (`===`) equality. See the `deep-eql` project page for info on the deep
             * equality algorithm: https://github.com/chaijs/deep-eql.
             *
             *     // Target object deeply (but not strictly) equals `{a: 1}`
             *     expect({a: 1}).to.deep.equal({a: 1});
             *     expect({a: 1}).to.not.equal({a: 1});
             *
             *     // Target array deeply (but not strictly) includes `{a: 1}`
             *     expect([{a: 1}]).to.deep.include({a: 1});
             *     expect([{a: 1}]).to.not.include({a: 1});
             *
             *     // Target object deeply (but not strictly) includes `x: {a: 1}`
             *     expect({x: {a: 1}}).to.deep.include({x: {a: 1}});
             *     expect({x: {a: 1}}).to.not.include({x: {a: 1}});
             *
             *     // Target array deeply (but not strictly) has member `{a: 1}`
             *     expect([{a: 1}]).to.have.deep.members([{a: 1}]);
             *     expect([{a: 1}]).to.not.have.members([{a: 1}]);
             *
             *     // Target set deeply (but not strictly) has key `{a: 1}`
             *     expect(new Set([{a: 1}])).to.have.deep.keys([{a: 1}]);
             *     expect(new Set([{a: 1}])).to.not.have.keys([{a: 1}]);
             *
             *     // Target object deeply (but not strictly) has property `x: {a: 1}`
             *     expect({x: {a: 1}}).to.have.deep.property('x', {a: 1});
             *     expect({x: {a: 1}}).to.not.have.property('x', {a: 1});
             *
             * @name deep
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('deep', function () {
              flag(this, 'deep', true)
            })

            /**
             * ### .nested
             *
             * Enables dot- and bracket-notation in all `.property` and `.include`
             * assertions that follow in the chain.
             *
             *     expect({a: {b: ['x', 'y']}}).to.have.nested.property('a.b[1]');
             *     expect({a: {b: ['x', 'y']}}).to.nested.include({'a.b[1]': 'y'});
             *
             * If `.` or `[]` are part of an actual property name, they can be escaped by
             * adding two backslashes before them.
             *
             *     expect({'.a': {'[b]': 'x'}}).to.have.nested.property('\\.a.\\[b\\]');
             *     expect({'.a': {'[b]': 'x'}}).to.nested.include({'\\.a.\\[b\\]': 'x'});
             *
             * `.nested` cannot be combined with `.own`.
             *
             * @name nested
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('nested', function () {
              flag(this, 'nested', true)
            })

            /**
             * ### .own
             *
             * Causes all `.property` and `.include` assertions that follow in the chain
             * to ignore inherited properties.
             *
             *     Object.prototype.b = 2;
             *
             *     expect({a: 1}).to.have.own.property('a');
             *     expect({a: 1}).to.have.property('b');
             *     expect({a: 1}).to.not.have.own.property('b');
             *
             *     expect({a: 1}).to.own.include({a: 1});
             *     expect({a: 1}).to.include({b: 2}).but.not.own.include({b: 2});
             *
             * `.own` cannot be combined with `.nested`.
             *
             * @name own
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('own', function () {
              flag(this, 'own', true)
            })

            /**
             * ### .ordered
             *
             * Causes all `.members` assertions that follow in the chain to require that
             * members be in the same order.
             *
             *     expect([1, 2]).to.have.ordered.members([1, 2])
             *       .but.not.have.ordered.members([2, 1]);
             *
             * When `.include` and `.ordered` are combined, the ordering begins at the
             * start of both arrays.
             *
             *     expect([1, 2, 3]).to.include.ordered.members([1, 2])
             *       .but.not.include.ordered.members([2, 3]);
             *
             * @name ordered
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('ordered', function () {
              flag(this, 'ordered', true)
            })

            /**
             * ### .any
             *
             * Causes all `.keys` assertions that follow in the chain to only require that
             * the target have at least one of the given keys. This is the opposite of
             * `.all`, which requires that the target have all of the given keys.
             *
             *     expect({a: 1, b: 2}).to.not.have.any.keys('c', 'd');
             *
             * See the `.keys` doc for guidance on when to use `.any` or `.all`.
             *
             * @name any
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('any', function () {
              flag(this, 'any', true)
              flag(this, 'all', false)
            })

            /**
             * ### .all
             *
             * Causes all `.keys` assertions that follow in the chain to require that the
             * target have all of the given keys. This is the opposite of `.any`, which
             * only requires that the target have at least one of the given keys.
             *
             *     expect({a: 1, b: 2}).to.have.all.keys('a', 'b');
             *
             * Note that `.all` is used by default when neither `.all` nor `.any` are
             * added earlier in the chain. However, it's often best to add `.all` anyway
             * because it improves readability.
             *
             * See the `.keys` doc for guidance on when to use `.any` or `.all`.
             *
             * @name all
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('all', function () {
              flag(this, 'all', true)
              flag(this, 'any', false)
            })

            /**
             * ### .a(type[, msg])
             *
             * Asserts that the target's type is equal to the given string `type`. Types
             * are case insensitive. See the `type-detect` project page for info on the
             * type detection algorithm: https://github.com/chaijs/type-detect.
             *
             *     expect('foo').to.be.a('string');
             *     expect({a: 1}).to.be.an('object');
             *     expect(null).to.be.a('null');
             *     expect(undefined).to.be.an('undefined');
             *     expect(new Error).to.be.an('error');
             *     expect(Promise.resolve()).to.be.a('promise');
             *     expect(new Float32Array).to.be.a('float32array');
             *     expect(Symbol()).to.be.a('symbol');
             *
             * `.a` supports objects that have a custom type set via `Symbol.toStringTag`.
             *
             *     var myObj = {
             *       [Symbol.toStringTag]: 'myCustomType'
             *     };
             *
             *     expect(myObj).to.be.a('myCustomType').but.not.an('object');
             *
             * It's often best to use `.a` to check a target's type before making more
             * assertions on the same target. That way, you avoid unexpected behavior from
             * any assertion that does different things based on the target's type.
             *
             *     expect([1, 2, 3]).to.be.an('array').that.includes(2);
             *     expect([]).to.be.an('array').that.is.empty;
             *
             * Add `.not` earlier in the chain to negate `.a`. However, it's often best to
             * assert that the target is the expected type, rather than asserting that it
             * isn't one of many unexpected types.
             *
             *     expect('foo').to.be.a('string'); // Recommended
             *     expect('foo').to.not.be.an('array'); // Not recommended
             *
             * `.a` accepts an optional `msg` argument which is a custom error message to
             * show when the assertion fails. The message can also be given as the second
             * argument to `expect`.
             *
             *     expect(1).to.be.a('string', 'nooo why fail??');
             *     expect(1, 'nooo why fail??').to.be.a('string');
             *
             * `.a` can also be used as a language chain to improve the readability of
             * your assertions.
             *
             *     expect({b: 2}).to.have.a.property('b');
             *
             * The alias `.an` can be used interchangeably with `.a`.
             *
             * @name a
             * @alias an
             * @param {String} type
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function an(type, msg) {
              if (msg) flag(this, 'message', msg)
              type = type.toLowerCase()
              var obj = flag(this, 'object'),
                article = ~['a', 'e', 'i', 'o', 'u'].indexOf(type.charAt(0))
                  ? 'an '
                  : 'a '

              this.assert(
                type === _.type(obj).toLowerCase(),
                'expected #{this} to be ' + article + type,
                'expected #{this} not to be ' + article + type
              )
            }

            Assertion.addChainableMethod('an', an)
            Assertion.addChainableMethod('a', an)

            /**
             * ### .include(val[, msg])
             *
             * When the target is a string, `.include` asserts that the given string `val`
             * is a substring of the target.
             *
             *     expect('foobar').to.include('foo');
             *
             * When the target is an array, `.include` asserts that the given `val` is a
             * member of the target.
             *
             *     expect([1, 2, 3]).to.include(2);
             *
             * When the target is an object, `.include` asserts that the given object
             * `val`'s properties are a subset of the target's properties.
             *
             *     expect({a: 1, b: 2, c: 3}).to.include({a: 1, b: 2});
             *
             * When the target is a Set or WeakSet, `.include` asserts that the given `val` is a
             * member of the target. SameValueZero equality algorithm is used.
             *
             *     expect(new Set([1, 2])).to.include(2);
             *
             * When the target is a Map, `.include` asserts that the given `val` is one of
             * the values of the target. SameValueZero equality algorithm is used.
             *
             *     expect(new Map([['a', 1], ['b', 2]])).to.include(2);
             *
             * Because `.include` does different things based on the target's type, it's
             * important to check the target's type before using `.include`. See the `.a`
             * doc for info on testing a target's type.
             *
             *     expect([1, 2, 3]).to.be.an('array').that.includes(2);
             *
             * By default, strict (`===`) equality is used to compare array members and
             * object properties. Add `.deep` earlier in the chain to use deep equality
             * instead (WeakSet targets are not supported). See the `deep-eql` project
             * page for info on the deep equality algorithm: https://github.com/chaijs/deep-eql.
             *
             *     // Target array deeply (but not strictly) includes `{a: 1}`
             *     expect([{a: 1}]).to.deep.include({a: 1});
             *     expect([{a: 1}]).to.not.include({a: 1});
             *
             *     // Target object deeply (but not strictly) includes `x: {a: 1}`
             *     expect({x: {a: 1}}).to.deep.include({x: {a: 1}});
             *     expect({x: {a: 1}}).to.not.include({x: {a: 1}});
             *
             * By default, all of the target's properties are searched when working with
             * objects. This includes properties that are inherited and/or non-enumerable.
             * Add `.own` earlier in the chain to exclude the target's inherited
             * properties from the search.
             *
             *     Object.prototype.b = 2;
             *
             *     expect({a: 1}).to.own.include({a: 1});
             *     expect({a: 1}).to.include({b: 2}).but.not.own.include({b: 2});
             *
             * Note that a target object is always only searched for `val`'s own
             * enumerable properties.
             *
             * `.deep` and `.own` can be combined.
             *
             *     expect({a: {b: 2}}).to.deep.own.include({a: {b: 2}});
             *
             * Add `.nested` earlier in the chain to enable dot- and bracket-notation when
             * referencing nested properties.
             *
             *     expect({a: {b: ['x', 'y']}}).to.nested.include({'a.b[1]': 'y'});
             *
             * If `.` or `[]` are part of an actual property name, they can be escaped by
             * adding two backslashes before them.
             *
             *     expect({'.a': {'[b]': 2}}).to.nested.include({'\\.a.\\[b\\]': 2});
             *
             * `.deep` and `.nested` can be combined.
             *
             *     expect({a: {b: [{c: 3}]}}).to.deep.nested.include({'a.b[0]': {c: 3}});
             *
             * `.own` and `.nested` cannot be combined.
             *
             * Add `.not` earlier in the chain to negate `.include`.
             *
             *     expect('foobar').to.not.include('taco');
             *     expect([1, 2, 3]).to.not.include(4);
             *
             * However, it's dangerous to negate `.include` when the target is an object.
             * The problem is that it creates uncertain expectations by asserting that the
             * target object doesn't have all of `val`'s key/value pairs but may or may
             * not have some of them. It's often best to identify the exact output that's
             * expected, and then write an assertion that only accepts that exact output.
             *
             * When the target object isn't even expected to have `val`'s keys, it's
             * often best to assert exactly that.
             *
             *     expect({c: 3}).to.not.have.any.keys('a', 'b'); // Recommended
             *     expect({c: 3}).to.not.include({a: 1, b: 2}); // Not recommended
             *
             * When the target object is expected to have `val`'s keys, it's often best to
             * assert that each of the properties has its expected value, rather than
             * asserting that each property doesn't have one of many unexpected values.
             *
             *     expect({a: 3, b: 4}).to.include({a: 3, b: 4}); // Recommended
             *     expect({a: 3, b: 4}).to.not.include({a: 1, b: 2}); // Not recommended
             *
             * `.include` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`.
             *
             *     expect([1, 2, 3]).to.include(4, 'nooo why fail??');
             *     expect([1, 2, 3], 'nooo why fail??').to.include(4);
             *
             * `.include` can also be used as a language chain, causing all `.members` and
             * `.keys` assertions that follow in the chain to require the target to be a
             * superset of the expected set, rather than an identical set. Note that
             * `.members` ignores duplicates in the subset when `.include` is added.
             *
             *     // Target object's keys are a superset of ['a', 'b'] but not identical
             *     expect({a: 1, b: 2, c: 3}).to.include.all.keys('a', 'b');
             *     expect({a: 1, b: 2, c: 3}).to.not.have.all.keys('a', 'b');
             *
             *     // Target array is a superset of [1, 2] but not identical
             *     expect([1, 2, 3]).to.include.members([1, 2]);
             *     expect([1, 2, 3]).to.not.have.members([1, 2]);
             *
             *     // Duplicates in the subset are ignored
             *     expect([1, 2, 3]).to.include.members([1, 2, 2, 2]);
             *
             * Note that adding `.any` earlier in the chain causes the `.keys` assertion
             * to ignore `.include`.
             *
             *     // Both assertions are identical
             *     expect({a: 1}).to.include.any.keys('a', 'b');
             *     expect({a: 1}).to.have.any.keys('a', 'b');
             *
             * The aliases `.includes`, `.contain`, and `.contains` can be used
             * interchangeably with `.include`.
             *
             * @name include
             * @alias contain
             * @alias includes
             * @alias contains
             * @param {Mixed} val
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function SameValueZero(a, b) {
              return (_.isNaN(a) && _.isNaN(b)) || a === b
            }

            function includeChainingBehavior() {
              flag(this, 'contains', true)
            }

            function include(val, msg) {
              if (msg) flag(this, 'message', msg)

              var obj = flag(this, 'object'),
                objType = _.type(obj).toLowerCase(),
                flagMsg = flag(this, 'message'),
                negate = flag(this, 'negate'),
                ssfi = flag(this, 'ssfi'),
                isDeep = flag(this, 'deep'),
                descriptor = isDeep ? 'deep ' : ''

              flagMsg = flagMsg ? flagMsg + ': ' : ''

              var included = false

              switch (objType) {
                case 'string':
                  included = obj.indexOf(val) !== -1
                  break

                case 'weakset':
                  if (isDeep) {
                    throw new AssertionError(
                      flagMsg + 'unable to use .deep.include with WeakSet',
                      undefined,
                      ssfi
                    )
                  }

                  included = obj.has(val)
                  break

                case 'map':
                  var isEql = isDeep ? _.eql : SameValueZero
                  obj.forEach(function (item) {
                    included = included || isEql(item, val)
                  })
                  break

                case 'set':
                  if (isDeep) {
                    obj.forEach(function (item) {
                      included = included || _.eql(item, val)
                    })
                  } else {
                    included = obj.has(val)
                  }
                  break

                case 'array':
                  if (isDeep) {
                    included = obj.some(function (item) {
                      return _.eql(item, val)
                    })
                  } else {
                    included = obj.indexOf(val) !== -1
                  }
                  break

                default:
                  // This block is for asserting a subset of properties in an object.
                  // `_.expectTypes` isn't used here because `.include` should work with
                  // objects with a custom `@@toStringTag`.
                  if (val !== Object(val)) {
                    throw new AssertionError(
                      flagMsg +
                        'the given combination of arguments (' +
                        objType +
                        ' and ' +
                        _.type(val).toLowerCase() +
                        ')' +
                        ' is invalid for this assertion. ' +
                        'You can use an array, a map, an object, a set, a string, ' +
                        'or a weakset instead of a ' +
                        _.type(val).toLowerCase(),
                      undefined,
                      ssfi
                    )
                  }

                  var props = Object.keys(val),
                    firstErr = null,
                    numErrs = 0

                  props.forEach(function (prop) {
                    var propAssertion = new Assertion(obj)
                    _.transferFlags(this, propAssertion, true)
                    flag(propAssertion, 'lockSsfi', true)

                    if (!negate || props.length === 1) {
                      propAssertion.property(prop, val[prop])
                      return
                    }

                    try {
                      propAssertion.property(prop, val[prop])
                    } catch (err) {
                      if (
                        !_.checkError.compatibleConstructor(err, AssertionError)
                      ) {
                        throw err
                      }
                      if (firstErr === null) firstErr = err
                      numErrs++
                    }
                  }, this)

                  // When validating .not.include with multiple properties, we only want
                  // to throw an assertion error if all of the properties are included,
                  // in which case we throw the first property assertion error that we
                  // encountered.
                  if (negate && props.length > 1 && numErrs === props.length) {
                    throw firstErr
                  }
                  return
              }

              // Assert inclusion in collection or substring in a string.
              this.assert(
                included,
                'expected #{this} to ' +
                  descriptor +
                  'include ' +
                  _.inspect(val),
                'expected #{this} to not ' +
                  descriptor +
                  'include ' +
                  _.inspect(val)
              )
            }

            Assertion.addChainableMethod(
              'include',
              include,
              includeChainingBehavior
            )
            Assertion.addChainableMethod(
              'contain',
              include,
              includeChainingBehavior
            )
            Assertion.addChainableMethod(
              'contains',
              include,
              includeChainingBehavior
            )
            Assertion.addChainableMethod(
              'includes',
              include,
              includeChainingBehavior
            )

            /**
             * ### .ok
             *
             * Asserts that the target is a truthy value (considered `true` in boolean context).
             * However, it's often best to assert that the target is strictly (`===`) or
             * deeply equal to its expected value.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.be.ok; // Not recommended
             *
             *     expect(true).to.be.true; // Recommended
             *     expect(true).to.be.ok; // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.ok`.
             *
             *     expect(0).to.equal(0); // Recommended
             *     expect(0).to.not.be.ok; // Not recommended
             *
             *     expect(false).to.be.false; // Recommended
             *     expect(false).to.not.be.ok; // Not recommended
             *
             *     expect(null).to.be.null; // Recommended
             *     expect(null).to.not.be.ok; // Not recommended
             *
             *     expect(undefined).to.be.undefined; // Recommended
             *     expect(undefined).to.not.be.ok; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect(false, 'nooo why fail??').to.be.ok;
             *
             * @name ok
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('ok', function () {
              this.assert(
                flag(this, 'object'),
                'expected #{this} to be truthy',
                'expected #{this} to be falsy'
              )
            })

            /**
             * ### .true
             *
             * Asserts that the target is strictly (`===`) equal to `true`.
             *
             *     expect(true).to.be.true;
             *
             * Add `.not` earlier in the chain to negate `.true`. However, it's often best
             * to assert that the target is equal to its expected value, rather than not
             * equal to `true`.
             *
             *     expect(false).to.be.false; // Recommended
             *     expect(false).to.not.be.true; // Not recommended
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.not.be.true; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect(false, 'nooo why fail??').to.be.true;
             *
             * @name true
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('true', function () {
              this.assert(
                true === flag(this, 'object'),
                'expected #{this} to be true',
                'expected #{this} to be false',
                flag(this, 'negate') ? false : true
              )
            })

            /**
             * ### .false
             *
             * Asserts that the target is strictly (`===`) equal to `false`.
             *
             *     expect(false).to.be.false;
             *
             * Add `.not` earlier in the chain to negate `.false`. However, it's often
             * best to assert that the target is equal to its expected value, rather than
             * not equal to `false`.
             *
             *     expect(true).to.be.true; // Recommended
             *     expect(true).to.not.be.false; // Not recommended
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.not.be.false; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect(true, 'nooo why fail??').to.be.false;
             *
             * @name false
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('false', function () {
              this.assert(
                false === flag(this, 'object'),
                'expected #{this} to be false',
                'expected #{this} to be true',
                flag(this, 'negate') ? true : false
              )
            })

            /**
             * ### .null
             *
             * Asserts that the target is strictly (`===`) equal to `null`.
             *
             *     expect(null).to.be.null;
             *
             * Add `.not` earlier in the chain to negate `.null`. However, it's often best
             * to assert that the target is equal to its expected value, rather than not
             * equal to `null`.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.not.be.null; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect(42, 'nooo why fail??').to.be.null;
             *
             * @name null
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('null', function () {
              this.assert(
                null === flag(this, 'object'),
                'expected #{this} to be null',
                'expected #{this} not to be null'
              )
            })

            /**
             * ### .undefined
             *
             * Asserts that the target is strictly (`===`) equal to `undefined`.
             *
             *     expect(undefined).to.be.undefined;
             *
             * Add `.not` earlier in the chain to negate `.undefined`. However, it's often
             * best to assert that the target is equal to its expected value, rather than
             * not equal to `undefined`.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.not.be.undefined; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect(42, 'nooo why fail??').to.be.undefined;
             *
             * @name undefined
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('undefined', function () {
              this.assert(
                undefined === flag(this, 'object'),
                'expected #{this} to be undefined',
                'expected #{this} not to be undefined'
              )
            })

            /**
             * ### .NaN
             *
             * Asserts that the target is exactly `NaN`.
             *
             *     expect(NaN).to.be.NaN;
             *
             * Add `.not` earlier in the chain to negate `.NaN`. However, it's often best
             * to assert that the target is equal to its expected value, rather than not
             * equal to `NaN`.
             *
             *     expect('foo').to.equal('foo'); // Recommended
             *     expect('foo').to.not.be.NaN; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect(42, 'nooo why fail??').to.be.NaN;
             *
             * @name NaN
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('NaN', function () {
              this.assert(
                _.isNaN(flag(this, 'object')),
                'expected #{this} to be NaN',
                'expected #{this} not to be NaN'
              )
            })

            /**
             * ### .exist
             *
             * Asserts that the target is not strictly (`===`) equal to either `null` or
             * `undefined`. However, it's often best to assert that the target is equal to
             * its expected value.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.exist; // Not recommended
             *
             *     expect(0).to.equal(0); // Recommended
             *     expect(0).to.exist; // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.exist`.
             *
             *     expect(null).to.be.null; // Recommended
             *     expect(null).to.not.exist; // Not recommended
             *
             *     expect(undefined).to.be.undefined; // Recommended
             *     expect(undefined).to.not.exist; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect(null, 'nooo why fail??').to.exist;
             *
             * The alias `.exists` can be used interchangeably with `.exist`.
             *
             * @name exist
             * @alias exists
             * @namespace BDD
             * @api public
             */

            function assertExist() {
              var val = flag(this, 'object')
              this.assert(
                val !== null && val !== undefined,
                'expected #{this} to exist',
                'expected #{this} to not exist'
              )
            }

            Assertion.addProperty('exist', assertExist)
            Assertion.addProperty('exists', assertExist)

            /**
             * ### .empty
             *
             * When the target is a string or array, `.empty` asserts that the target's
             * `length` property is strictly (`===`) equal to `0`.
             *
             *     expect([]).to.be.empty;
             *     expect('').to.be.empty;
             *
             * When the target is a map or set, `.empty` asserts that the target's `size`
             * property is strictly equal to `0`.
             *
             *     expect(new Set()).to.be.empty;
             *     expect(new Map()).to.be.empty;
             *
             * When the target is a non-function object, `.empty` asserts that the target
             * doesn't have any own enumerable properties. Properties with Symbol-based
             * keys are excluded from the count.
             *
             *     expect({}).to.be.empty;
             *
             * Because `.empty` does different things based on the target's type, it's
             * important to check the target's type before using `.empty`. See the `.a`
             * doc for info on testing a target's type.
             *
             *     expect([]).to.be.an('array').that.is.empty;
             *
             * Add `.not` earlier in the chain to negate `.empty`. However, it's often
             * best to assert that the target contains its expected number of values,
             * rather than asserting that it's not empty.
             *
             *     expect([1, 2, 3]).to.have.lengthOf(3); // Recommended
             *     expect([1, 2, 3]).to.not.be.empty; // Not recommended
             *
             *     expect(new Set([1, 2, 3])).to.have.property('size', 3); // Recommended
             *     expect(new Set([1, 2, 3])).to.not.be.empty; // Not recommended
             *
             *     expect(Object.keys({a: 1})).to.have.lengthOf(1); // Recommended
             *     expect({a: 1}).to.not.be.empty; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect([1, 2, 3], 'nooo why fail??').to.be.empty;
             *
             * @name empty
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('empty', function () {
              var val = flag(this, 'object'),
                ssfi = flag(this, 'ssfi'),
                flagMsg = flag(this, 'message'),
                itemsCount

              flagMsg = flagMsg ? flagMsg + ': ' : ''

              switch (_.type(val).toLowerCase()) {
                case 'array':
                case 'string':
                  itemsCount = val.length
                  break
                case 'map':
                case 'set':
                  itemsCount = val.size
                  break
                case 'weakmap':
                case 'weakset':
                  throw new AssertionError(
                    flagMsg + '.empty was passed a weak collection',
                    undefined,
                    ssfi
                  )
                case 'function':
                  var msg =
                    flagMsg + '.empty was passed a function ' + _.getName(val)
                  throw new AssertionError(msg.trim(), undefined, ssfi)
                default:
                  if (val !== Object(val)) {
                    throw new AssertionError(
                      flagMsg +
                        '.empty was passed non-string primitive ' +
                        _.inspect(val),
                      undefined,
                      ssfi
                    )
                  }
                  itemsCount = Object.keys(val).length
              }

              this.assert(
                0 === itemsCount,
                'expected #{this} to be empty',
                'expected #{this} not to be empty'
              )
            })

            /**
             * ### .arguments
             *
             * Asserts that the target is an `arguments` object.
             *
             *     function test () {
             *       expect(arguments).to.be.arguments;
             *     }
             *
             *     test();
             *
             * Add `.not` earlier in the chain to negate `.arguments`. However, it's often
             * best to assert which type the target is expected to be, rather than
             * asserting that it’s not an `arguments` object.
             *
             *     expect('foo').to.be.a('string'); // Recommended
             *     expect('foo').to.not.be.arguments; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect({}, 'nooo why fail??').to.be.arguments;
             *
             * The alias `.Arguments` can be used interchangeably with `.arguments`.
             *
             * @name arguments
             * @alias Arguments
             * @namespace BDD
             * @api public
             */

            function checkArguments() {
              var obj = flag(this, 'object'),
                type = _.type(obj)
              this.assert(
                'Arguments' === type,
                'expected #{this} to be arguments but got ' + type,
                'expected #{this} to not be arguments'
              )
            }

            Assertion.addProperty('arguments', checkArguments)
            Assertion.addProperty('Arguments', checkArguments)

            /**
             * ### .equal(val[, msg])
             *
             * Asserts that the target is strictly (`===`) equal to the given `val`.
             *
             *     expect(1).to.equal(1);
             *     expect('foo').to.equal('foo');
             *
             * Add `.deep` earlier in the chain to use deep equality instead. See the
             * `deep-eql` project page for info on the deep equality algorithm:
             * https://github.com/chaijs/deep-eql.
             *
             *     // Target object deeply (but not strictly) equals `{a: 1}`
             *     expect({a: 1}).to.deep.equal({a: 1});
             *     expect({a: 1}).to.not.equal({a: 1});
             *
             *     // Target array deeply (but not strictly) equals `[1, 2]`
             *     expect([1, 2]).to.deep.equal([1, 2]);
             *     expect([1, 2]).to.not.equal([1, 2]);
             *
             * Add `.not` earlier in the chain to negate `.equal`. However, it's often
             * best to assert that the target is equal to its expected value, rather than
             * not equal to one of countless unexpected values.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.not.equal(2); // Not recommended
             *
             * `.equal` accepts an optional `msg` argument which is a custom error message
             * to show when the assertion fails. The message can also be given as the
             * second argument to `expect`.
             *
             *     expect(1).to.equal(2, 'nooo why fail??');
             *     expect(1, 'nooo why fail??').to.equal(2);
             *
             * The aliases `.equals` and `eq` can be used interchangeably with `.equal`.
             *
             * @name equal
             * @alias equals
             * @alias eq
             * @param {Mixed} val
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertEqual(val, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object')
              if (flag(this, 'deep')) {
                var prevLockSsfi = flag(this, 'lockSsfi')
                flag(this, 'lockSsfi', true)
                this.eql(val)
                flag(this, 'lockSsfi', prevLockSsfi)
              } else {
                this.assert(
                  val === obj,
                  'expected #{this} to equal #{exp}',
                  'expected #{this} to not equal #{exp}',
                  val,
                  this._obj,
                  true
                )
              }
            }

            Assertion.addMethod('equal', assertEqual)
            Assertion.addMethod('equals', assertEqual)
            Assertion.addMethod('eq', assertEqual)

            /**
             * ### .eql(obj[, msg])
             *
             * Asserts that the target is deeply equal to the given `obj`. See the
             * `deep-eql` project page for info on the deep equality algorithm:
             * https://github.com/chaijs/deep-eql.
             *
             *     // Target object is deeply (but not strictly) equal to {a: 1}
             *     expect({a: 1}).to.eql({a: 1}).but.not.equal({a: 1});
             *
             *     // Target array is deeply (but not strictly) equal to [1, 2]
             *     expect([1, 2]).to.eql([1, 2]).but.not.equal([1, 2]);
             *
             * Add `.not` earlier in the chain to negate `.eql`. However, it's often best
             * to assert that the target is deeply equal to its expected value, rather
             * than not deeply equal to one of countless unexpected values.
             *
             *     expect({a: 1}).to.eql({a: 1}); // Recommended
             *     expect({a: 1}).to.not.eql({b: 2}); // Not recommended
             *
             * `.eql` accepts an optional `msg` argument which is a custom error message
             * to show when the assertion fails. The message can also be given as the
             * second argument to `expect`.
             *
             *     expect({a: 1}).to.eql({b: 2}, 'nooo why fail??');
             *     expect({a: 1}, 'nooo why fail??').to.eql({b: 2});
             *
             * The alias `.eqls` can be used interchangeably with `.eql`.
             *
             * The `.deep.equal` assertion is almost identical to `.eql` but with one
             * difference: `.deep.equal` causes deep equality comparisons to also be used
             * for any other assertions that follow in the chain.
             *
             * @name eql
             * @alias eqls
             * @param {Mixed} obj
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertEql(obj, msg) {
              if (msg) flag(this, 'message', msg)
              this.assert(
                _.eql(obj, flag(this, 'object')),
                'expected #{this} to deeply equal #{exp}',
                'expected #{this} to not deeply equal #{exp}',
                obj,
                this._obj,
                true
              )
            }

            Assertion.addMethod('eql', assertEql)
            Assertion.addMethod('eqls', assertEql)

            /**
             * ### .above(n[, msg])
             *
             * Asserts that the target is a number or a date greater than the given number or date `n` respectively.
             * However, it's often best to assert that the target is equal to its expected
             * value.
             *
             *     expect(2).to.equal(2); // Recommended
             *     expect(2).to.be.above(1); // Not recommended
             *
             * Add `.lengthOf` earlier in the chain to assert that the target's `length`
             * or `size` is greater than the given number `n`.
             *
             *     expect('foo').to.have.lengthOf(3); // Recommended
             *     expect('foo').to.have.lengthOf.above(2); // Not recommended
             *
             *     expect([1, 2, 3]).to.have.lengthOf(3); // Recommended
             *     expect([1, 2, 3]).to.have.lengthOf.above(2); // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.above`.
             *
             *     expect(2).to.equal(2); // Recommended
             *     expect(1).to.not.be.above(2); // Not recommended
             *
             * `.above` accepts an optional `msg` argument which is a custom error message
             * to show when the assertion fails. The message can also be given as the
             * second argument to `expect`.
             *
             *     expect(1).to.be.above(2, 'nooo why fail??');
             *     expect(1, 'nooo why fail??').to.be.above(2);
             *
             * The aliases `.gt` and `.greaterThan` can be used interchangeably with
             * `.above`.
             *
             * @name above
             * @alias gt
             * @alias greaterThan
             * @param {Number} n
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertAbove(n, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                doLength = flag(this, 'doLength'),
                flagMsg = flag(this, 'message'),
                msgPrefix = flagMsg ? flagMsg + ': ' : '',
                ssfi = flag(this, 'ssfi'),
                objType = _.type(obj).toLowerCase(),
                nType = _.type(n).toLowerCase(),
                errorMessage,
                shouldThrow = true

              if (doLength && objType !== 'map' && objType !== 'set') {
                new Assertion(obj, flagMsg, ssfi, true).to.have.property(
                  'length'
                )
              }

              if (!doLength && objType === 'date' && nType !== 'date') {
                errorMessage =
                  msgPrefix + 'the argument to above must be a date'
              } else if (
                nType !== 'number' &&
                (doLength || objType === 'number')
              ) {
                errorMessage =
                  msgPrefix + 'the argument to above must be a number'
              } else if (
                !doLength &&
                objType !== 'date' &&
                objType !== 'number'
              ) {
                var printObj = objType === 'string' ? "'" + obj + "'" : obj
                errorMessage =
                  msgPrefix +
                  'expected ' +
                  printObj +
                  ' to be a number or a date'
              } else {
                shouldThrow = false
              }

              if (shouldThrow) {
                throw new AssertionError(errorMessage, undefined, ssfi)
              }

              if (doLength) {
                var descriptor = 'length',
                  itemsCount
                if (objType === 'map' || objType === 'set') {
                  descriptor = 'size'
                  itemsCount = obj.size
                } else {
                  itemsCount = obj.length
                }
                this.assert(
                  itemsCount > n,
                  'expected #{this} to have a ' +
                    descriptor +
                    ' above #{exp} but got #{act}',
                  'expected #{this} to not have a ' +
                    descriptor +
                    ' above #{exp}',
                  n,
                  itemsCount
                )
              } else {
                this.assert(
                  obj > n,
                  'expected #{this} to be above #{exp}',
                  'expected #{this} to be at most #{exp}',
                  n
                )
              }
            }

            Assertion.addMethod('above', assertAbove)
            Assertion.addMethod('gt', assertAbove)
            Assertion.addMethod('greaterThan', assertAbove)

            /**
             * ### .least(n[, msg])
             *
             * Asserts that the target is a number or a date greater than or equal to the given
             * number or date `n` respectively. However, it's often best to assert that the target is equal to
             * its expected value.
             *
             *     expect(2).to.equal(2); // Recommended
             *     expect(2).to.be.at.least(1); // Not recommended
             *     expect(2).to.be.at.least(2); // Not recommended
             *
             * Add `.lengthOf` earlier in the chain to assert that the target's `length`
             * or `size` is greater than or equal to the given number `n`.
             *
             *     expect('foo').to.have.lengthOf(3); // Recommended
             *     expect('foo').to.have.lengthOf.at.least(2); // Not recommended
             *
             *     expect([1, 2, 3]).to.have.lengthOf(3); // Recommended
             *     expect([1, 2, 3]).to.have.lengthOf.at.least(2); // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.least`.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.not.be.at.least(2); // Not recommended
             *
             * `.least` accepts an optional `msg` argument which is a custom error message
             * to show when the assertion fails. The message can also be given as the
             * second argument to `expect`.
             *
             *     expect(1).to.be.at.least(2, 'nooo why fail??');
             *     expect(1, 'nooo why fail??').to.be.at.least(2);
             *
             * The aliases `.gte` and `.greaterThanOrEqual` can be used interchangeably with
             * `.least`.
             *
             * @name least
             * @alias gte
             * @alias greaterThanOrEqual
             * @param {Number} n
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertLeast(n, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                doLength = flag(this, 'doLength'),
                flagMsg = flag(this, 'message'),
                msgPrefix = flagMsg ? flagMsg + ': ' : '',
                ssfi = flag(this, 'ssfi'),
                objType = _.type(obj).toLowerCase(),
                nType = _.type(n).toLowerCase(),
                errorMessage,
                shouldThrow = true

              if (doLength && objType !== 'map' && objType !== 'set') {
                new Assertion(obj, flagMsg, ssfi, true).to.have.property(
                  'length'
                )
              }

              if (!doLength && objType === 'date' && nType !== 'date') {
                errorMessage =
                  msgPrefix + 'the argument to least must be a date'
              } else if (
                nType !== 'number' &&
                (doLength || objType === 'number')
              ) {
                errorMessage =
                  msgPrefix + 'the argument to least must be a number'
              } else if (
                !doLength &&
                objType !== 'date' &&
                objType !== 'number'
              ) {
                var printObj = objType === 'string' ? "'" + obj + "'" : obj
                errorMessage =
                  msgPrefix +
                  'expected ' +
                  printObj +
                  ' to be a number or a date'
              } else {
                shouldThrow = false
              }

              if (shouldThrow) {
                throw new AssertionError(errorMessage, undefined, ssfi)
              }

              if (doLength) {
                var descriptor = 'length',
                  itemsCount
                if (objType === 'map' || objType === 'set') {
                  descriptor = 'size'
                  itemsCount = obj.size
                } else {
                  itemsCount = obj.length
                }
                this.assert(
                  itemsCount >= n,
                  'expected #{this} to have a ' +
                    descriptor +
                    ' at least #{exp} but got #{act}',
                  'expected #{this} to have a ' + descriptor + ' below #{exp}',
                  n,
                  itemsCount
                )
              } else {
                this.assert(
                  obj >= n,
                  'expected #{this} to be at least #{exp}',
                  'expected #{this} to be below #{exp}',
                  n
                )
              }
            }

            Assertion.addMethod('least', assertLeast)
            Assertion.addMethod('gte', assertLeast)
            Assertion.addMethod('greaterThanOrEqual', assertLeast)

            /**
             * ### .below(n[, msg])
             *
             * Asserts that the target is a number or a date less than the given number or date `n` respectively.
             * However, it's often best to assert that the target is equal to its expected
             * value.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.be.below(2); // Not recommended
             *
             * Add `.lengthOf` earlier in the chain to assert that the target's `length`
             * or `size` is less than the given number `n`.
             *
             *     expect('foo').to.have.lengthOf(3); // Recommended
             *     expect('foo').to.have.lengthOf.below(4); // Not recommended
             *
             *     expect([1, 2, 3]).to.have.length(3); // Recommended
             *     expect([1, 2, 3]).to.have.lengthOf.below(4); // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.below`.
             *
             *     expect(2).to.equal(2); // Recommended
             *     expect(2).to.not.be.below(1); // Not recommended
             *
             * `.below` accepts an optional `msg` argument which is a custom error message
             * to show when the assertion fails. The message can also be given as the
             * second argument to `expect`.
             *
             *     expect(2).to.be.below(1, 'nooo why fail??');
             *     expect(2, 'nooo why fail??').to.be.below(1);
             *
             * The aliases `.lt` and `.lessThan` can be used interchangeably with
             * `.below`.
             *
             * @name below
             * @alias lt
             * @alias lessThan
             * @param {Number} n
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertBelow(n, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                doLength = flag(this, 'doLength'),
                flagMsg = flag(this, 'message'),
                msgPrefix = flagMsg ? flagMsg + ': ' : '',
                ssfi = flag(this, 'ssfi'),
                objType = _.type(obj).toLowerCase(),
                nType = _.type(n).toLowerCase(),
                errorMessage,
                shouldThrow = true

              if (doLength && objType !== 'map' && objType !== 'set') {
                new Assertion(obj, flagMsg, ssfi, true).to.have.property(
                  'length'
                )
              }

              if (!doLength && objType === 'date' && nType !== 'date') {
                errorMessage =
                  msgPrefix + 'the argument to below must be a date'
              } else if (
                nType !== 'number' &&
                (doLength || objType === 'number')
              ) {
                errorMessage =
                  msgPrefix + 'the argument to below must be a number'
              } else if (
                !doLength &&
                objType !== 'date' &&
                objType !== 'number'
              ) {
                var printObj = objType === 'string' ? "'" + obj + "'" : obj
                errorMessage =
                  msgPrefix +
                  'expected ' +
                  printObj +
                  ' to be a number or a date'
              } else {
                shouldThrow = false
              }

              if (shouldThrow) {
                throw new AssertionError(errorMessage, undefined, ssfi)
              }

              if (doLength) {
                var descriptor = 'length',
                  itemsCount
                if (objType === 'map' || objType === 'set') {
                  descriptor = 'size'
                  itemsCount = obj.size
                } else {
                  itemsCount = obj.length
                }
                this.assert(
                  itemsCount < n,
                  'expected #{this} to have a ' +
                    descriptor +
                    ' below #{exp} but got #{act}',
                  'expected #{this} to not have a ' +
                    descriptor +
                    ' below #{exp}',
                  n,
                  itemsCount
                )
              } else {
                this.assert(
                  obj < n,
                  'expected #{this} to be below #{exp}',
                  'expected #{this} to be at least #{exp}',
                  n
                )
              }
            }

            Assertion.addMethod('below', assertBelow)
            Assertion.addMethod('lt', assertBelow)
            Assertion.addMethod('lessThan', assertBelow)

            /**
             * ### .most(n[, msg])
             *
             * Asserts that the target is a number or a date less than or equal to the given number
             * or date `n` respectively. However, it's often best to assert that the target is equal to its
             * expected value.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.be.at.most(2); // Not recommended
             *     expect(1).to.be.at.most(1); // Not recommended
             *
             * Add `.lengthOf` earlier in the chain to assert that the target's `length`
             * or `size` is less than or equal to the given number `n`.
             *
             *     expect('foo').to.have.lengthOf(3); // Recommended
             *     expect('foo').to.have.lengthOf.at.most(4); // Not recommended
             *
             *     expect([1, 2, 3]).to.have.lengthOf(3); // Recommended
             *     expect([1, 2, 3]).to.have.lengthOf.at.most(4); // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.most`.
             *
             *     expect(2).to.equal(2); // Recommended
             *     expect(2).to.not.be.at.most(1); // Not recommended
             *
             * `.most` accepts an optional `msg` argument which is a custom error message
             * to show when the assertion fails. The message can also be given as the
             * second argument to `expect`.
             *
             *     expect(2).to.be.at.most(1, 'nooo why fail??');
             *     expect(2, 'nooo why fail??').to.be.at.most(1);
             *
             * The aliases `.lte` and `.lessThanOrEqual` can be used interchangeably with
             * `.most`.
             *
             * @name most
             * @alias lte
             * @alias lessThanOrEqual
             * @param {Number} n
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertMost(n, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                doLength = flag(this, 'doLength'),
                flagMsg = flag(this, 'message'),
                msgPrefix = flagMsg ? flagMsg + ': ' : '',
                ssfi = flag(this, 'ssfi'),
                objType = _.type(obj).toLowerCase(),
                nType = _.type(n).toLowerCase(),
                errorMessage,
                shouldThrow = true

              if (doLength && objType !== 'map' && objType !== 'set') {
                new Assertion(obj, flagMsg, ssfi, true).to.have.property(
                  'length'
                )
              }

              if (!doLength && objType === 'date' && nType !== 'date') {
                errorMessage = msgPrefix + 'the argument to most must be a date'
              } else if (
                nType !== 'number' &&
                (doLength || objType === 'number')
              ) {
                errorMessage =
                  msgPrefix + 'the argument to most must be a number'
              } else if (
                !doLength &&
                objType !== 'date' &&
                objType !== 'number'
              ) {
                var printObj = objType === 'string' ? "'" + obj + "'" : obj
                errorMessage =
                  msgPrefix +
                  'expected ' +
                  printObj +
                  ' to be a number or a date'
              } else {
                shouldThrow = false
              }

              if (shouldThrow) {
                throw new AssertionError(errorMessage, undefined, ssfi)
              }

              if (doLength) {
                var descriptor = 'length',
                  itemsCount
                if (objType === 'map' || objType === 'set') {
                  descriptor = 'size'
                  itemsCount = obj.size
                } else {
                  itemsCount = obj.length
                }
                this.assert(
                  itemsCount <= n,
                  'expected #{this} to have a ' +
                    descriptor +
                    ' at most #{exp} but got #{act}',
                  'expected #{this} to have a ' + descriptor + ' above #{exp}',
                  n,
                  itemsCount
                )
              } else {
                this.assert(
                  obj <= n,
                  'expected #{this} to be at most #{exp}',
                  'expected #{this} to be above #{exp}',
                  n
                )
              }
            }

            Assertion.addMethod('most', assertMost)
            Assertion.addMethod('lte', assertMost)
            Assertion.addMethod('lessThanOrEqual', assertMost)

            /**
             * ### .within(start, finish[, msg])
             *
             * Asserts that the target is a number or a date greater than or equal to the given
             * number or date `start`, and less than or equal to the given number or date `finish` respectively.
             * However, it's often best to assert that the target is equal to its expected
             * value.
             *
             *     expect(2).to.equal(2); // Recommended
             *     expect(2).to.be.within(1, 3); // Not recommended
             *     expect(2).to.be.within(2, 3); // Not recommended
             *     expect(2).to.be.within(1, 2); // Not recommended
             *
             * Add `.lengthOf` earlier in the chain to assert that the target's `length`
             * or `size` is greater than or equal to the given number `start`, and less
             * than or equal to the given number `finish`.
             *
             *     expect('foo').to.have.lengthOf(3); // Recommended
             *     expect('foo').to.have.lengthOf.within(2, 4); // Not recommended
             *
             *     expect([1, 2, 3]).to.have.lengthOf(3); // Recommended
             *     expect([1, 2, 3]).to.have.lengthOf.within(2, 4); // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.within`.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.not.be.within(2, 4); // Not recommended
             *
             * `.within` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`.
             *
             *     expect(4).to.be.within(1, 3, 'nooo why fail??');
             *     expect(4, 'nooo why fail??').to.be.within(1, 3);
             *
             * @name within
             * @param {Number} start lower bound inclusive
             * @param {Number} finish upper bound inclusive
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            Assertion.addMethod('within', function (start, finish, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                doLength = flag(this, 'doLength'),
                flagMsg = flag(this, 'message'),
                msgPrefix = flagMsg ? flagMsg + ': ' : '',
                ssfi = flag(this, 'ssfi'),
                objType = _.type(obj).toLowerCase(),
                startType = _.type(start).toLowerCase(),
                finishType = _.type(finish).toLowerCase(),
                errorMessage,
                shouldThrow = true,
                range =
                  startType === 'date' && finishType === 'date'
                    ? start.toUTCString() + '..' + finish.toUTCString()
                    : start + '..' + finish

              if (doLength && objType !== 'map' && objType !== 'set') {
                new Assertion(obj, flagMsg, ssfi, true).to.have.property(
                  'length'
                )
              }

              if (
                !doLength &&
                objType === 'date' &&
                (startType !== 'date' || finishType !== 'date')
              ) {
                errorMessage =
                  msgPrefix + 'the arguments to within must be dates'
              } else if (
                (startType !== 'number' || finishType !== 'number') &&
                (doLength || objType === 'number')
              ) {
                errorMessage =
                  msgPrefix + 'the arguments to within must be numbers'
              } else if (
                !doLength &&
                objType !== 'date' &&
                objType !== 'number'
              ) {
                var printObj = objType === 'string' ? "'" + obj + "'" : obj
                errorMessage =
                  msgPrefix +
                  'expected ' +
                  printObj +
                  ' to be a number or a date'
              } else {
                shouldThrow = false
              }

              if (shouldThrow) {
                throw new AssertionError(errorMessage, undefined, ssfi)
              }

              if (doLength) {
                var descriptor = 'length',
                  itemsCount
                if (objType === 'map' || objType === 'set') {
                  descriptor = 'size'
                  itemsCount = obj.size
                } else {
                  itemsCount = obj.length
                }
                this.assert(
                  itemsCount >= start && itemsCount <= finish,
                  'expected #{this} to have a ' +
                    descriptor +
                    ' within ' +
                    range,
                  'expected #{this} to not have a ' +
                    descriptor +
                    ' within ' +
                    range
                )
              } else {
                this.assert(
                  obj >= start && obj <= finish,
                  'expected #{this} to be within ' + range,
                  'expected #{this} to not be within ' + range
                )
              }
            })

            /**
             * ### .instanceof(constructor[, msg])
             *
             * Asserts that the target is an instance of the given `constructor`.
             *
             *     function Cat () { }
             *
             *     expect(new Cat()).to.be.an.instanceof(Cat);
             *     expect([1, 2]).to.be.an.instanceof(Array);
             *
             * Add `.not` earlier in the chain to negate `.instanceof`.
             *
             *     expect({a: 1}).to.not.be.an.instanceof(Array);
             *
             * `.instanceof` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`.
             *
             *     expect(1).to.be.an.instanceof(Array, 'nooo why fail??');
             *     expect(1, 'nooo why fail??').to.be.an.instanceof(Array);
             *
             * Due to limitations in ES5, `.instanceof` may not always work as expected
             * when using a transpiler such as Babel or TypeScript. In particular, it may
             * produce unexpected results when subclassing built-in object such as
             * `Array`, `Error`, and `Map`. See your transpiler's docs for details:
             *
             * - ([Babel](https://babeljs.io/docs/usage/caveats/#classes))
             * - ([TypeScript](https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#extending-built-ins-like-error-array-and-map-may-no-longer-work))
             *
             * The alias `.instanceOf` can be used interchangeably with `.instanceof`.
             *
             * @name instanceof
             * @param {Constructor} constructor
             * @param {String} msg _optional_
             * @alias instanceOf
             * @namespace BDD
             * @api public
             */

            function assertInstanceOf(constructor, msg) {
              if (msg) flag(this, 'message', msg)

              var target = flag(this, 'object')
              var ssfi = flag(this, 'ssfi')
              var flagMsg = flag(this, 'message')

              try {
                var isInstanceOf = target instanceof constructor
              } catch (err) {
                if (err instanceof TypeError) {
                  flagMsg = flagMsg ? flagMsg + ': ' : ''
                  throw new AssertionError(
                    flagMsg +
                      'The instanceof assertion needs a constructor but ' +
                      _.type(constructor) +
                      ' was given.',
                    undefined,
                    ssfi
                  )
                }
                throw err
              }

              var name = _.getName(constructor)
              if (name === null) {
                name = 'an unnamed constructor'
              }

              this.assert(
                isInstanceOf,
                'expected #{this} to be an instance of ' + name,
                'expected #{this} to not be an instance of ' + name
              )
            }

            Assertion.addMethod('instanceof', assertInstanceOf)
            Assertion.addMethod('instanceOf', assertInstanceOf)

            /**
             * ### .property(name[, val[, msg]])
             *
             * Asserts that the target has a property with the given key `name`.
             *
             *     expect({a: 1}).to.have.property('a');
             *
             * When `val` is provided, `.property` also asserts that the property's value
             * is equal to the given `val`.
             *
             *     expect({a: 1}).to.have.property('a', 1);
             *
             * By default, strict (`===`) equality is used. Add `.deep` earlier in the
             * chain to use deep equality instead. See the `deep-eql` project page for
             * info on the deep equality algorithm: https://github.com/chaijs/deep-eql.
             *
             *     // Target object deeply (but not strictly) has property `x: {a: 1}`
             *     expect({x: {a: 1}}).to.have.deep.property('x', {a: 1});
             *     expect({x: {a: 1}}).to.not.have.property('x', {a: 1});
             *
             * The target's enumerable and non-enumerable properties are always included
             * in the search. By default, both own and inherited properties are included.
             * Add `.own` earlier in the chain to exclude inherited properties from the
             * search.
             *
             *     Object.prototype.b = 2;
             *
             *     expect({a: 1}).to.have.own.property('a');
             *     expect({a: 1}).to.have.own.property('a', 1);
             *     expect({a: 1}).to.have.property('b');
             *     expect({a: 1}).to.not.have.own.property('b');
             *
             * `.deep` and `.own` can be combined.
             *
             *     expect({x: {a: 1}}).to.have.deep.own.property('x', {a: 1});
             *
             * Add `.nested` earlier in the chain to enable dot- and bracket-notation when
             * referencing nested properties.
             *
             *     expect({a: {b: ['x', 'y']}}).to.have.nested.property('a.b[1]');
             *     expect({a: {b: ['x', 'y']}}).to.have.nested.property('a.b[1]', 'y');
             *
             * If `.` or `[]` are part of an actual property name, they can be escaped by
             * adding two backslashes before them.
             *
             *     expect({'.a': {'[b]': 'x'}}).to.have.nested.property('\\.a.\\[b\\]');
             *
             * `.deep` and `.nested` can be combined.
             *
             *     expect({a: {b: [{c: 3}]}})
             *       .to.have.deep.nested.property('a.b[0]', {c: 3});
             *
             * `.own` and `.nested` cannot be combined.
             *
             * Add `.not` earlier in the chain to negate `.property`.
             *
             *     expect({a: 1}).to.not.have.property('b');
             *
             * However, it's dangerous to negate `.property` when providing `val`. The
             * problem is that it creates uncertain expectations by asserting that the
             * target either doesn't have a property with the given key `name`, or that it
             * does have a property with the given key `name` but its value isn't equal to
             * the given `val`. It's often best to identify the exact output that's
             * expected, and then write an assertion that only accepts that exact output.
             *
             * When the target isn't expected to have a property with the given key
             * `name`, it's often best to assert exactly that.
             *
             *     expect({b: 2}).to.not.have.property('a'); // Recommended
             *     expect({b: 2}).to.not.have.property('a', 1); // Not recommended
             *
             * When the target is expected to have a property with the given key `name`,
             * it's often best to assert that the property has its expected value, rather
             * than asserting that it doesn't have one of many unexpected values.
             *
             *     expect({a: 3}).to.have.property('a', 3); // Recommended
             *     expect({a: 3}).to.not.have.property('a', 1); // Not recommended
             *
             * `.property` changes the target of any assertions that follow in the chain
             * to be the value of the property from the original target object.
             *
             *     expect({a: 1}).to.have.property('a').that.is.a('number');
             *
             * `.property` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`. When not providing `val`, only use the
             * second form.
             *
             *     // Recommended
             *     expect({a: 1}).to.have.property('a', 2, 'nooo why fail??');
             *     expect({a: 1}, 'nooo why fail??').to.have.property('a', 2);
             *     expect({a: 1}, 'nooo why fail??').to.have.property('b');
             *
             *     // Not recommended
             *     expect({a: 1}).to.have.property('b', undefined, 'nooo why fail??');
             *
             * The above assertion isn't the same thing as not providing `val`. Instead,
             * it's asserting that the target object has a `b` property that's equal to
             * `undefined`.
             *
             * The assertions `.ownProperty` and `.haveOwnProperty` can be used
             * interchangeably with `.own.property`.
             *
             * @name property
             * @param {String} name
             * @param {Mixed} val (optional)
             * @param {String} msg _optional_
             * @returns value of property for chaining
             * @namespace BDD
             * @api public
             */

            function assertProperty(name, val, msg) {
              if (msg) flag(this, 'message', msg)

              var isNested = flag(this, 'nested'),
                isOwn = flag(this, 'own'),
                flagMsg = flag(this, 'message'),
                obj = flag(this, 'object'),
                ssfi = flag(this, 'ssfi'),
                nameType = typeof name

              flagMsg = flagMsg ? flagMsg + ': ' : ''

              if (isNested) {
                if (nameType !== 'string') {
                  throw new AssertionError(
                    flagMsg +
                      'the argument to property must be a string when using nested syntax',
                    undefined,
                    ssfi
                  )
                }
              } else {
                if (
                  nameType !== 'string' &&
                  nameType !== 'number' &&
                  nameType !== 'symbol'
                ) {
                  throw new AssertionError(
                    flagMsg +
                      'the argument to property must be a string, number, or symbol',
                    undefined,
                    ssfi
                  )
                }
              }

              if (isNested && isOwn) {
                throw new AssertionError(
                  flagMsg + 'The "nested" and "own" flags cannot be combined.',
                  undefined,
                  ssfi
                )
              }

              if (obj === null || obj === undefined) {
                throw new AssertionError(
                  flagMsg + 'Target cannot be null or undefined.',
                  undefined,
                  ssfi
                )
              }

              var isDeep = flag(this, 'deep'),
                negate = flag(this, 'negate'),
                pathInfo = isNested ? _.getPathInfo(obj, name) : null,
                value = isNested ? pathInfo.value : obj[name]

              var descriptor = ''
              if (isDeep) descriptor += 'deep '
              if (isOwn) descriptor += 'own '
              if (isNested) descriptor += 'nested '
              descriptor += 'property '

              var hasProperty
              if (isOwn)
                hasProperty = Object.prototype.hasOwnProperty.call(obj, name)
              else if (isNested) hasProperty = pathInfo.exists
              else hasProperty = _.hasProperty(obj, name)

              // When performing a negated assertion for both name and val, merely having
              // a property with the given name isn't enough to cause the assertion to
              // fail. It must both have a property with the given name, and the value of
              // that property must equal the given val. Therefore, skip this assertion in
              // favor of the next.
              if (!negate || arguments.length === 1) {
                this.assert(
                  hasProperty,
                  'expected #{this} to have ' + descriptor + _.inspect(name),
                  'expected #{this} to not have ' + descriptor + _.inspect(name)
                )
              }

              if (arguments.length > 1) {
                this.assert(
                  hasProperty && (isDeep ? _.eql(val, value) : val === value),
                  'expected #{this} to have ' +
                    descriptor +
                    _.inspect(name) +
                    ' of #{exp}, but got #{act}',
                  'expected #{this} to not have ' +
                    descriptor +
                    _.inspect(name) +
                    ' of #{act}',
                  val,
                  value
                )
              }

              flag(this, 'object', value)
            }

            Assertion.addMethod('property', assertProperty)

            function assertOwnProperty(name, value, msg) {
              flag(this, 'own', true)
              assertProperty.apply(this, arguments)
            }

            Assertion.addMethod('ownProperty', assertOwnProperty)
            Assertion.addMethod('haveOwnProperty', assertOwnProperty)

            /**
             * ### .ownPropertyDescriptor(name[, descriptor[, msg]])
             *
             * Asserts that the target has its own property descriptor with the given key
             * `name`. Enumerable and non-enumerable properties are included in the
             * search.
             *
             *     expect({a: 1}).to.have.ownPropertyDescriptor('a');
             *
             * When `descriptor` is provided, `.ownPropertyDescriptor` also asserts that
             * the property's descriptor is deeply equal to the given `descriptor`. See
             * the `deep-eql` project page for info on the deep equality algorithm:
             * https://github.com/chaijs/deep-eql.
             *
             *     expect({a: 1}).to.have.ownPropertyDescriptor('a', {
             *       configurable: true,
             *       enumerable: true,
             *       writable: true,
             *       value: 1,
             *     });
             *
             * Add `.not` earlier in the chain to negate `.ownPropertyDescriptor`.
             *
             *     expect({a: 1}).to.not.have.ownPropertyDescriptor('b');
             *
             * However, it's dangerous to negate `.ownPropertyDescriptor` when providing
             * a `descriptor`. The problem is that it creates uncertain expectations by
             * asserting that the target either doesn't have a property descriptor with
             * the given key `name`, or that it does have a property descriptor with the
             * given key `name` but it’s not deeply equal to the given `descriptor`. It's
             * often best to identify the exact output that's expected, and then write an
             * assertion that only accepts that exact output.
             *
             * When the target isn't expected to have a property descriptor with the given
             * key `name`, it's often best to assert exactly that.
             *
             *     // Recommended
             *     expect({b: 2}).to.not.have.ownPropertyDescriptor('a');
             *
             *     // Not recommended
             *     expect({b: 2}).to.not.have.ownPropertyDescriptor('a', {
             *       configurable: true,
             *       enumerable: true,
             *       writable: true,
             *       value: 1,
             *     });
             *
             * When the target is expected to have a property descriptor with the given
             * key `name`, it's often best to assert that the property has its expected
             * descriptor, rather than asserting that it doesn't have one of many
             * unexpected descriptors.
             *
             *     // Recommended
             *     expect({a: 3}).to.have.ownPropertyDescriptor('a', {
             *       configurable: true,
             *       enumerable: true,
             *       writable: true,
             *       value: 3,
             *     });
             *
             *     // Not recommended
             *     expect({a: 3}).to.not.have.ownPropertyDescriptor('a', {
             *       configurable: true,
             *       enumerable: true,
             *       writable: true,
             *       value: 1,
             *     });
             *
             * `.ownPropertyDescriptor` changes the target of any assertions that follow
             * in the chain to be the value of the property descriptor from the original
             * target object.
             *
             *     expect({a: 1}).to.have.ownPropertyDescriptor('a')
             *       .that.has.property('enumerable', true);
             *
             * `.ownPropertyDescriptor` accepts an optional `msg` argument which is a
             * custom error message to show when the assertion fails. The message can also
             * be given as the second argument to `expect`. When not providing
             * `descriptor`, only use the second form.
             *
             *     // Recommended
             *     expect({a: 1}).to.have.ownPropertyDescriptor('a', {
             *       configurable: true,
             *       enumerable: true,
             *       writable: true,
             *       value: 2,
             *     }, 'nooo why fail??');
             *
             *     // Recommended
             *     expect({a: 1}, 'nooo why fail??').to.have.ownPropertyDescriptor('a', {
             *       configurable: true,
             *       enumerable: true,
             *       writable: true,
             *       value: 2,
             *     });
             *
             *     // Recommended
             *     expect({a: 1}, 'nooo why fail??').to.have.ownPropertyDescriptor('b');
             *
             *     // Not recommended
             *     expect({a: 1})
             *       .to.have.ownPropertyDescriptor('b', undefined, 'nooo why fail??');
             *
             * The above assertion isn't the same thing as not providing `descriptor`.
             * Instead, it's asserting that the target object has a `b` property
             * descriptor that's deeply equal to `undefined`.
             *
             * The alias `.haveOwnPropertyDescriptor` can be used interchangeably with
             * `.ownPropertyDescriptor`.
             *
             * @name ownPropertyDescriptor
             * @alias haveOwnPropertyDescriptor
             * @param {String} name
             * @param {Object} descriptor _optional_
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertOwnPropertyDescriptor(name, descriptor, msg) {
              if (typeof descriptor === 'string') {
                msg = descriptor
                descriptor = null
              }
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object')
              var actualDescriptor = Object.getOwnPropertyDescriptor(
                Object(obj),
                name
              )
              if (actualDescriptor && descriptor) {
                this.assert(
                  _.eql(descriptor, actualDescriptor),
                  'expected the own property descriptor for ' +
                    _.inspect(name) +
                    ' on #{this} to match ' +
                    _.inspect(descriptor) +
                    ', got ' +
                    _.inspect(actualDescriptor),
                  'expected the own property descriptor for ' +
                    _.inspect(name) +
                    ' on #{this} to not match ' +
                    _.inspect(descriptor),
                  descriptor,
                  actualDescriptor,
                  true
                )
              } else {
                this.assert(
                  actualDescriptor,
                  'expected #{this} to have an own property descriptor for ' +
                    _.inspect(name),
                  'expected #{this} to not have an own property descriptor for ' +
                    _.inspect(name)
                )
              }
              flag(this, 'object', actualDescriptor)
            }

            Assertion.addMethod(
              'ownPropertyDescriptor',
              assertOwnPropertyDescriptor
            )
            Assertion.addMethod(
              'haveOwnPropertyDescriptor',
              assertOwnPropertyDescriptor
            )

            /**
             * ### .lengthOf(n[, msg])
             *
             * Asserts that the target's `length` or `size` is equal to the given number
             * `n`.
             *
             *     expect([1, 2, 3]).to.have.lengthOf(3);
             *     expect('foo').to.have.lengthOf(3);
             *     expect(new Set([1, 2, 3])).to.have.lengthOf(3);
             *     expect(new Map([['a', 1], ['b', 2], ['c', 3]])).to.have.lengthOf(3);
             *
             * Add `.not` earlier in the chain to negate `.lengthOf`. However, it's often
             * best to assert that the target's `length` property is equal to its expected
             * value, rather than not equal to one of many unexpected values.
             *
             *     expect('foo').to.have.lengthOf(3); // Recommended
             *     expect('foo').to.not.have.lengthOf(4); // Not recommended
             *
             * `.lengthOf` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`.
             *
             *     expect([1, 2, 3]).to.have.lengthOf(2, 'nooo why fail??');
             *     expect([1, 2, 3], 'nooo why fail??').to.have.lengthOf(2);
             *
             * `.lengthOf` can also be used as a language chain, causing all `.above`,
             * `.below`, `.least`, `.most`, and `.within` assertions that follow in the
             * chain to use the target's `length` property as the target. However, it's
             * often best to assert that the target's `length` property is equal to its
             * expected length, rather than asserting that its `length` property falls
             * within some range of values.
             *
             *     // Recommended
             *     expect([1, 2, 3]).to.have.lengthOf(3);
             *
             *     // Not recommended
             *     expect([1, 2, 3]).to.have.lengthOf.above(2);
             *     expect([1, 2, 3]).to.have.lengthOf.below(4);
             *     expect([1, 2, 3]).to.have.lengthOf.at.least(3);
             *     expect([1, 2, 3]).to.have.lengthOf.at.most(3);
             *     expect([1, 2, 3]).to.have.lengthOf.within(2,4);
             *
             * Due to a compatibility issue, the alias `.length` can't be chained directly
             * off of an uninvoked method such as `.a`. Therefore, `.length` can't be used
             * interchangeably with `.lengthOf` in every situation. It's recommended to
             * always use `.lengthOf` instead of `.length`.
             *
             *     expect([1, 2, 3]).to.have.a.length(3); // incompatible; throws error
             *     expect([1, 2, 3]).to.have.a.lengthOf(3);  // passes as expected
             *
             * @name lengthOf
             * @alias length
             * @param {Number} n
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertLengthChain() {
              flag(this, 'doLength', true)
            }

            function assertLength(n, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                objType = _.type(obj).toLowerCase(),
                flagMsg = flag(this, 'message'),
                ssfi = flag(this, 'ssfi'),
                descriptor = 'length',
                itemsCount

              switch (objType) {
                case 'map':
                case 'set':
                  descriptor = 'size'
                  itemsCount = obj.size
                  break
                default:
                  new Assertion(obj, flagMsg, ssfi, true).to.have.property(
                    'length'
                  )
                  itemsCount = obj.length
              }

              this.assert(
                itemsCount == n,
                'expected #{this} to have a ' +
                  descriptor +
                  ' of #{exp} but got #{act}',
                'expected #{this} to not have a ' + descriptor + ' of #{act}',
                n,
                itemsCount
              )
            }

            Assertion.addChainableMethod(
              'length',
              assertLength,
              assertLengthChain
            )
            Assertion.addChainableMethod(
              'lengthOf',
              assertLength,
              assertLengthChain
            )

            /**
             * ### .match(re[, msg])
             *
             * Asserts that the target matches the given regular expression `re`.
             *
             *     expect('foobar').to.match(/^foo/);
             *
             * Add `.not` earlier in the chain to negate `.match`.
             *
             *     expect('foobar').to.not.match(/taco/);
             *
             * `.match` accepts an optional `msg` argument which is a custom error message
             * to show when the assertion fails. The message can also be given as the
             * second argument to `expect`.
             *
             *     expect('foobar').to.match(/taco/, 'nooo why fail??');
             *     expect('foobar', 'nooo why fail??').to.match(/taco/);
             *
             * The alias `.matches` can be used interchangeably with `.match`.
             *
             * @name match
             * @alias matches
             * @param {RegExp} re
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */
            function assertMatch(re, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object')
              this.assert(
                re.exec(obj),
                'expected #{this} to match ' + re,
                'expected #{this} not to match ' + re
              )
            }

            Assertion.addMethod('match', assertMatch)
            Assertion.addMethod('matches', assertMatch)

            /**
             * ### .string(str[, msg])
             *
             * Asserts that the target string contains the given substring `str`.
             *
             *     expect('foobar').to.have.string('bar');
             *
             * Add `.not` earlier in the chain to negate `.string`.
             *
             *     expect('foobar').to.not.have.string('taco');
             *
             * `.string` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`.
             *
             *     expect('foobar').to.have.string('taco', 'nooo why fail??');
             *     expect('foobar', 'nooo why fail??').to.have.string('taco');
             *
             * @name string
             * @param {String} str
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            Assertion.addMethod('string', function (str, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                flagMsg = flag(this, 'message'),
                ssfi = flag(this, 'ssfi')
              new Assertion(obj, flagMsg, ssfi, true).is.a('string')

              this.assert(
                ~obj.indexOf(str),
                'expected #{this} to contain ' + _.inspect(str),
                'expected #{this} to not contain ' + _.inspect(str)
              )
            })

            /**
             * ### .keys(key1[, key2[, ...]])
             *
             * Asserts that the target object, array, map, or set has the given keys. Only
             * the target's own inherited properties are included in the search.
             *
             * When the target is an object or array, keys can be provided as one or more
             * string arguments, a single array argument, or a single object argument. In
             * the latter case, only the keys in the given object matter; the values are
             * ignored.
             *
             *     expect({a: 1, b: 2}).to.have.all.keys('a', 'b');
             *     expect(['x', 'y']).to.have.all.keys(0, 1);
             *
             *     expect({a: 1, b: 2}).to.have.all.keys(['a', 'b']);
             *     expect(['x', 'y']).to.have.all.keys([0, 1]);
             *
             *     expect({a: 1, b: 2}).to.have.all.keys({a: 4, b: 5}); // ignore 4 and 5
             *     expect(['x', 'y']).to.have.all.keys({0: 4, 1: 5}); // ignore 4 and 5
             *
             * When the target is a map or set, each key must be provided as a separate
             * argument.
             *
             *     expect(new Map([['a', 1], ['b', 2]])).to.have.all.keys('a', 'b');
             *     expect(new Set(['a', 'b'])).to.have.all.keys('a', 'b');
             *
             * Because `.keys` does different things based on the target's type, it's
             * important to check the target's type before using `.keys`. See the `.a` doc
             * for info on testing a target's type.
             *
             *     expect({a: 1, b: 2}).to.be.an('object').that.has.all.keys('a', 'b');
             *
             * By default, strict (`===`) equality is used to compare keys of maps and
             * sets. Add `.deep` earlier in the chain to use deep equality instead. See
             * the `deep-eql` project page for info on the deep equality algorithm:
             * https://github.com/chaijs/deep-eql.
             *
             *     // Target set deeply (but not strictly) has key `{a: 1}`
             *     expect(new Set([{a: 1}])).to.have.all.deep.keys([{a: 1}]);
             *     expect(new Set([{a: 1}])).to.not.have.all.keys([{a: 1}]);
             *
             * By default, the target must have all of the given keys and no more. Add
             * `.any` earlier in the chain to only require that the target have at least
             * one of the given keys. Also, add `.not` earlier in the chain to negate
             * `.keys`. It's often best to add `.any` when negating `.keys`, and to use
             * `.all` when asserting `.keys` without negation.
             *
             * When negating `.keys`, `.any` is preferred because `.not.any.keys` asserts
             * exactly what's expected of the output, whereas `.not.all.keys` creates
             * uncertain expectations.
             *
             *     // Recommended; asserts that target doesn't have any of the given keys
             *     expect({a: 1, b: 2}).to.not.have.any.keys('c', 'd');
             *
             *     // Not recommended; asserts that target doesn't have all of the given
             *     // keys but may or may not have some of them
             *     expect({a: 1, b: 2}).to.not.have.all.keys('c', 'd');
             *
             * When asserting `.keys` without negation, `.all` is preferred because
             * `.all.keys` asserts exactly what's expected of the output, whereas
             * `.any.keys` creates uncertain expectations.
             *
             *     // Recommended; asserts that target has all the given keys
             *     expect({a: 1, b: 2}).to.have.all.keys('a', 'b');
             *
             *     // Not recommended; asserts that target has at least one of the given
             *     // keys but may or may not have more of them
             *     expect({a: 1, b: 2}).to.have.any.keys('a', 'b');
             *
             * Note that `.all` is used by default when neither `.all` nor `.any` appear
             * earlier in the chain. However, it's often best to add `.all` anyway because
             * it improves readability.
             *
             *     // Both assertions are identical
             *     expect({a: 1, b: 2}).to.have.all.keys('a', 'b'); // Recommended
             *     expect({a: 1, b: 2}).to.have.keys('a', 'b'); // Not recommended
             *
             * Add `.include` earlier in the chain to require that the target's keys be a
             * superset of the expected keys, rather than identical sets.
             *
             *     // Target object's keys are a superset of ['a', 'b'] but not identical
             *     expect({a: 1, b: 2, c: 3}).to.include.all.keys('a', 'b');
             *     expect({a: 1, b: 2, c: 3}).to.not.have.all.keys('a', 'b');
             *
             * However, if `.any` and `.include` are combined, only the `.any` takes
             * effect. The `.include` is ignored in this case.
             *
             *     // Both assertions are identical
             *     expect({a: 1}).to.have.any.keys('a', 'b');
             *     expect({a: 1}).to.include.any.keys('a', 'b');
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect({a: 1}, 'nooo why fail??').to.have.key('b');
             *
             * The alias `.key` can be used interchangeably with `.keys`.
             *
             * @name keys
             * @alias key
             * @param {...String|Array|Object} keys
             * @namespace BDD
             * @api public
             */

            function assertKeys(keys) {
              var obj = flag(this, 'object'),
                objType = _.type(obj),
                keysType = _.type(keys),
                ssfi = flag(this, 'ssfi'),
                isDeep = flag(this, 'deep'),
                str,
                deepStr = '',
                actual,
                ok = true,
                flagMsg = flag(this, 'message')

              flagMsg = flagMsg ? flagMsg + ': ' : ''
              var mixedArgsMsg =
                flagMsg +
                'when testing keys against an object or an array you must give a single Array|Object|String argument or multiple String arguments'

              if (objType === 'Map' || objType === 'Set') {
                deepStr = isDeep ? 'deeply ' : ''
                actual = []

                // Map and Set '.keys' aren't supported in IE 11. Therefore, use .forEach.
                obj.forEach(function (val, key) {
                  actual.push(key)
                })

                if (keysType !== 'Array') {
                  keys = Array.prototype.slice.call(arguments)
                }
              } else {
                actual = _.getOwnEnumerableProperties(obj)

                switch (keysType) {
                  case 'Array':
                    if (arguments.length > 1) {
                      throw new AssertionError(mixedArgsMsg, undefined, ssfi)
                    }
                    break
                  case 'Object':
                    if (arguments.length > 1) {
                      throw new AssertionError(mixedArgsMsg, undefined, ssfi)
                    }
                    keys = Object.keys(keys)
                    break
                  default:
                    keys = Array.prototype.slice.call(arguments)
                }

                // Only stringify non-Symbols because Symbols would become "Symbol()"
                keys = keys.map(function (val) {
                  return typeof val === 'symbol' ? val : String(val)
                })
              }

              if (!keys.length) {
                throw new AssertionError(
                  flagMsg + 'keys required',
                  undefined,
                  ssfi
                )
              }

              var len = keys.length,
                any = flag(this, 'any'),
                all = flag(this, 'all'),
                expected = keys

              if (!any && !all) {
                all = true
              }

              // Has any
              if (any) {
                ok = expected.some(function (expectedKey) {
                  return actual.some(function (actualKey) {
                    if (isDeep) {
                      return _.eql(expectedKey, actualKey)
                    } else {
                      return expectedKey === actualKey
                    }
                  })
                })
              }

              // Has all
              if (all) {
                ok = expected.every(function (expectedKey) {
                  return actual.some(function (actualKey) {
                    if (isDeep) {
                      return _.eql(expectedKey, actualKey)
                    } else {
                      return expectedKey === actualKey
                    }
                  })
                })

                if (!flag(this, 'contains')) {
                  ok = ok && keys.length == actual.length
                }
              }

              // Key string
              if (len > 1) {
                keys = keys.map(function (key) {
                  return _.inspect(key)
                })
                var last = keys.pop()
                if (all) {
                  str = keys.join(', ') + ', and ' + last
                }
                if (any) {
                  str = keys.join(', ') + ', or ' + last
                }
              } else {
                str = _.inspect(keys[0])
              }

              // Form
              str = (len > 1 ? 'keys ' : 'key ') + str

              // Have / include
              str = (flag(this, 'contains') ? 'contain ' : 'have ') + str

              // Assertion
              this.assert(
                ok,
                'expected #{this} to ' + deepStr + str,
                'expected #{this} to not ' + deepStr + str,
                expected.slice(0).sort(_.compareByInspect),
                actual.sort(_.compareByInspect),
                true
              )
            }

            Assertion.addMethod('keys', assertKeys)
            Assertion.addMethod('key', assertKeys)

            /**
             * ### .throw([errorLike], [errMsgMatcher], [msg])
             *
             * When no arguments are provided, `.throw` invokes the target function and
             * asserts that an error is thrown.
             *
             *     var badFn = function () { throw new TypeError('Illegal salmon!'); };
             *
             *     expect(badFn).to.throw();
             *
             * When one argument is provided, and it's an error constructor, `.throw`
             * invokes the target function and asserts that an error is thrown that's an
             * instance of that error constructor.
             *
             *     var badFn = function () { throw new TypeError('Illegal salmon!'); };
             *
             *     expect(badFn).to.throw(TypeError);
             *
             * When one argument is provided, and it's an error instance, `.throw` invokes
             * the target function and asserts that an error is thrown that's strictly
             * (`===`) equal to that error instance.
             *
             *     var err = new TypeError('Illegal salmon!');
             *     var badFn = function () { throw err; };
             *
             *     expect(badFn).to.throw(err);
             *
             * When one argument is provided, and it's a string, `.throw` invokes the
             * target function and asserts that an error is thrown with a message that
             * contains that string.
             *
             *     var badFn = function () { throw new TypeError('Illegal salmon!'); };
             *
             *     expect(badFn).to.throw('salmon');
             *
             * When one argument is provided, and it's a regular expression, `.throw`
             * invokes the target function and asserts that an error is thrown with a
             * message that matches that regular expression.
             *
             *     var badFn = function () { throw new TypeError('Illegal salmon!'); };
             *
             *     expect(badFn).to.throw(/salmon/);
             *
             * When two arguments are provided, and the first is an error instance or
             * constructor, and the second is a string or regular expression, `.throw`
             * invokes the function and asserts that an error is thrown that fulfills both
             * conditions as described above.
             *
             *     var err = new TypeError('Illegal salmon!');
             *     var badFn = function () { throw err; };
             *
             *     expect(badFn).to.throw(TypeError, 'salmon');
             *     expect(badFn).to.throw(TypeError, /salmon/);
             *     expect(badFn).to.throw(err, 'salmon');
             *     expect(badFn).to.throw(err, /salmon/);
             *
             * Add `.not` earlier in the chain to negate `.throw`.
             *
             *     var goodFn = function () {};
             *
             *     expect(goodFn).to.not.throw();
             *
             * However, it's dangerous to negate `.throw` when providing any arguments.
             * The problem is that it creates uncertain expectations by asserting that the
             * target either doesn't throw an error, or that it throws an error but of a
             * different type than the given type, or that it throws an error of the given
             * type but with a message that doesn't include the given string. It's often
             * best to identify the exact output that's expected, and then write an
             * assertion that only accepts that exact output.
             *
             * When the target isn't expected to throw an error, it's often best to assert
             * exactly that.
             *
             *     var goodFn = function () {};
             *
             *     expect(goodFn).to.not.throw(); // Recommended
             *     expect(goodFn).to.not.throw(ReferenceError, 'x'); // Not recommended
             *
             * When the target is expected to throw an error, it's often best to assert
             * that the error is of its expected type, and has a message that includes an
             * expected string, rather than asserting that it doesn't have one of many
             * unexpected types, and doesn't have a message that includes some string.
             *
             *     var badFn = function () { throw new TypeError('Illegal salmon!'); };
             *
             *     expect(badFn).to.throw(TypeError, 'salmon'); // Recommended
             *     expect(badFn).to.not.throw(ReferenceError, 'x'); // Not recommended
             *
             * `.throw` changes the target of any assertions that follow in the chain to
             * be the error object that's thrown.
             *
             *     var err = new TypeError('Illegal salmon!');
             *     err.code = 42;
             *     var badFn = function () { throw err; };
             *
             *     expect(badFn).to.throw(TypeError).with.property('code', 42);
             *
             * `.throw` accepts an optional `msg` argument which is a custom error message
             * to show when the assertion fails. The message can also be given as the
             * second argument to `expect`. When not providing two arguments, always use
             * the second form.
             *
             *     var goodFn = function () {};
             *
             *     expect(goodFn).to.throw(TypeError, 'x', 'nooo why fail??');
             *     expect(goodFn, 'nooo why fail??').to.throw();
             *
             * Due to limitations in ES5, `.throw` may not always work as expected when
             * using a transpiler such as Babel or TypeScript. In particular, it may
             * produce unexpected results when subclassing the built-in `Error` object and
             * then passing the subclassed constructor to `.throw`. See your transpiler's
             * docs for details:
             *
             * - ([Babel](https://babeljs.io/docs/usage/caveats/#classes))
             * - ([TypeScript](https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#extending-built-ins-like-error-array-and-map-may-no-longer-work))
             *
             * Beware of some common mistakes when using the `throw` assertion. One common
             * mistake is to accidentally invoke the function yourself instead of letting
             * the `throw` assertion invoke the function for you. For example, when
             * testing if a function named `fn` throws, provide `fn` instead of `fn()` as
             * the target for the assertion.
             *
             *     expect(fn).to.throw();     // Good! Tests `fn` as desired
             *     expect(fn()).to.throw();   // Bad! Tests result of `fn()`, not `fn`
             *
             * If you need to assert that your function `fn` throws when passed certain
             * arguments, then wrap a call to `fn` inside of another function.
             *
             *     expect(function () { fn(42); }).to.throw();  // Function expression
             *     expect(() => fn(42)).to.throw();             // ES6 arrow function
             *
             * Another common mistake is to provide an object method (or any stand-alone
             * function that relies on `this`) as the target of the assertion. Doing so is
             * problematic because the `this` context will be lost when the function is
             * invoked by `.throw`; there's no way for it to know what `this` is supposed
             * to be. There are two ways around this problem. One solution is to wrap the
             * method or function call inside of another function. Another solution is to
             * use `bind`.
             *
             *     expect(function () { cat.meow(); }).to.throw();  // Function expression
             *     expect(() => cat.meow()).to.throw();             // ES6 arrow function
             *     expect(cat.meow.bind(cat)).to.throw();           // Bind
             *
             * Finally, it's worth mentioning that it's a best practice in JavaScript to
             * only throw `Error` and derivatives of `Error` such as `ReferenceError`,
             * `TypeError`, and user-defined objects that extend `Error`. No other type of
             * value will generate a stack trace when initialized. With that said, the
             * `throw` assertion does technically support any type of value being thrown,
             * not just `Error` and its derivatives.
             *
             * The aliases `.throws` and `.Throw` can be used interchangeably with
             * `.throw`.
             *
             * @name throw
             * @alias throws
             * @alias Throw
             * @param {Error|ErrorConstructor} errorLike
             * @param {String|RegExp} errMsgMatcher error message
             * @param {String} msg _optional_
             * @see https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Error#Error_types
             * @returns error for chaining (null if no error)
             * @namespace BDD
             * @api public
             */

            function assertThrows(errorLike, errMsgMatcher, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                ssfi = flag(this, 'ssfi'),
                flagMsg = flag(this, 'message'),
                negate = flag(this, 'negate') || false
              new Assertion(obj, flagMsg, ssfi, true).is.a('function')

              if (
                errorLike instanceof RegExp ||
                typeof errorLike === 'string'
              ) {
                errMsgMatcher = errorLike
                errorLike = null
              }

              var caughtErr
              try {
                obj()
              } catch (err) {
                caughtErr = err
              }

              // If we have the negate flag enabled and at least one valid argument it means we do expect an error
              // but we want it to match a given set of criteria
              var everyArgIsUndefined =
                errorLike === undefined && errMsgMatcher === undefined

              // If we've got the negate flag enabled and both args, we should only fail if both aren't compatible
              // See Issue #551 and PR #683@GitHub
              var everyArgIsDefined = Boolean(errorLike && errMsgMatcher)
              var errorLikeFail = false
              var errMsgMatcherFail = false

              // Checking if error was thrown
              if (everyArgIsUndefined || (!everyArgIsUndefined && !negate)) {
                // We need this to display results correctly according to their types
                var errorLikeString = 'an error'
                if (errorLike instanceof Error) {
                  errorLikeString = '#{exp}'
                } else if (errorLike) {
                  errorLikeString = _.checkError.getConstructorName(errorLike)
                }

                this.assert(
                  caughtErr,
                  'expected #{this} to throw ' + errorLikeString,
                  'expected #{this} to not throw an error but #{act} was thrown',
                  errorLike && errorLike.toString(),
                  caughtErr instanceof Error
                    ? caughtErr.toString()
                    : typeof caughtErr === 'string'
                    ? caughtErr
                    : caughtErr && _.checkError.getConstructorName(caughtErr)
                )
              }

              if (errorLike && caughtErr) {
                // We should compare instances only if `errorLike` is an instance of `Error`
                if (errorLike instanceof Error) {
                  var isCompatibleInstance = _.checkError.compatibleInstance(
                    caughtErr,
                    errorLike
                  )

                  if (isCompatibleInstance === negate) {
                    // These checks were created to ensure we won't fail too soon when we've got both args and a negate
                    // See Issue #551 and PR #683@GitHub
                    if (everyArgIsDefined && negate) {
                      errorLikeFail = true
                    } else {
                      this.assert(
                        negate,
                        'expected #{this} to throw #{exp} but #{act} was thrown',
                        'expected #{this} to not throw #{exp}' +
                          (caughtErr && !negate
                            ? ' but #{act} was thrown'
                            : ''),
                        errorLike.toString(),
                        caughtErr.toString()
                      )
                    }
                  }
                }

                var isCompatibleConstructor =
                  _.checkError.compatibleConstructor(caughtErr, errorLike)
                if (isCompatibleConstructor === negate) {
                  if (everyArgIsDefined && negate) {
                    errorLikeFail = true
                  } else {
                    this.assert(
                      negate,
                      'expected #{this} to throw #{exp} but #{act} was thrown',
                      'expected #{this} to not throw #{exp}' +
                        (caughtErr ? ' but #{act} was thrown' : ''),
                      errorLike instanceof Error
                        ? errorLike.toString()
                        : errorLike &&
                            _.checkError.getConstructorName(errorLike),
                      caughtErr instanceof Error
                        ? caughtErr.toString()
                        : caughtErr &&
                            _.checkError.getConstructorName(caughtErr)
                    )
                  }
                }
              }

              if (
                caughtErr &&
                errMsgMatcher !== undefined &&
                errMsgMatcher !== null
              ) {
                // Here we check compatible messages
                var placeholder = 'including'
                if (errMsgMatcher instanceof RegExp) {
                  placeholder = 'matching'
                }

                var isCompatibleMessage = _.checkError.compatibleMessage(
                  caughtErr,
                  errMsgMatcher
                )
                if (isCompatibleMessage === negate) {
                  if (everyArgIsDefined && negate) {
                    errMsgMatcherFail = true
                  } else {
                    this.assert(
                      negate,
                      'expected #{this} to throw error ' +
                        placeholder +
                        ' #{exp} but got #{act}',
                      'expected #{this} to throw error not ' +
                        placeholder +
                        ' #{exp}',
                      errMsgMatcher,
                      _.checkError.getMessage(caughtErr)
                    )
                  }
                }
              }

              // If both assertions failed and both should've matched we throw an error
              if (errorLikeFail && errMsgMatcherFail) {
                this.assert(
                  negate,
                  'expected #{this} to throw #{exp} but #{act} was thrown',
                  'expected #{this} to not throw #{exp}' +
                    (caughtErr ? ' but #{act} was thrown' : ''),
                  errorLike instanceof Error
                    ? errorLike.toString()
                    : errorLike && _.checkError.getConstructorName(errorLike),
                  caughtErr instanceof Error
                    ? caughtErr.toString()
                    : caughtErr && _.checkError.getConstructorName(caughtErr)
                )
              }

              flag(this, 'object', caughtErr)
            }

            Assertion.addMethod('throw', assertThrows)
            Assertion.addMethod('throws', assertThrows)
            Assertion.addMethod('Throw', assertThrows)

            /**
             * ### .respondTo(method[, msg])
             *
             * When the target is a non-function object, `.respondTo` asserts that the
             * target has a method with the given name `method`. The method can be own or
             * inherited, and it can be enumerable or non-enumerable.
             *
             *     function Cat () {}
             *     Cat.prototype.meow = function () {};
             *
             *     expect(new Cat()).to.respondTo('meow');
             *
             * When the target is a function, `.respondTo` asserts that the target's
             * `prototype` property has a method with the given name `method`. Again, the
             * method can be own or inherited, and it can be enumerable or non-enumerable.
             *
             *     function Cat () {}
             *     Cat.prototype.meow = function () {};
             *
             *     expect(Cat).to.respondTo('meow');
             *
             * Add `.itself` earlier in the chain to force `.respondTo` to treat the
             * target as a non-function object, even if it's a function. Thus, it asserts
             * that the target has a method with the given name `method`, rather than
             * asserting that the target's `prototype` property has a method with the
             * given name `method`.
             *
             *     function Cat () {}
             *     Cat.prototype.meow = function () {};
             *     Cat.hiss = function () {};
             *
             *     expect(Cat).itself.to.respondTo('hiss').but.not.respondTo('meow');
             *
             * When not adding `.itself`, it's important to check the target's type before
             * using `.respondTo`. See the `.a` doc for info on checking a target's type.
             *
             *     function Cat () {}
             *     Cat.prototype.meow = function () {};
             *
             *     expect(new Cat()).to.be.an('object').that.respondsTo('meow');
             *
             * Add `.not` earlier in the chain to negate `.respondTo`.
             *
             *     function Dog () {}
             *     Dog.prototype.bark = function () {};
             *
             *     expect(new Dog()).to.not.respondTo('meow');
             *
             * `.respondTo` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`.
             *
             *     expect({}).to.respondTo('meow', 'nooo why fail??');
             *     expect({}, 'nooo why fail??').to.respondTo('meow');
             *
             * The alias `.respondsTo` can be used interchangeably with `.respondTo`.
             *
             * @name respondTo
             * @alias respondsTo
             * @param {String} method
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function respondTo(method, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                itself = flag(this, 'itself'),
                context =
                  'function' === typeof obj && !itself
                    ? obj.prototype[method]
                    : obj[method]

              this.assert(
                'function' === typeof context,
                'expected #{this} to respond to ' + _.inspect(method),
                'expected #{this} to not respond to ' + _.inspect(method)
              )
            }

            Assertion.addMethod('respondTo', respondTo)
            Assertion.addMethod('respondsTo', respondTo)

            /**
             * ### .itself
             *
             * Forces all `.respondTo` assertions that follow in the chain to behave as if
             * the target is a non-function object, even if it's a function. Thus, it
             * causes `.respondTo` to assert that the target has a method with the given
             * name, rather than asserting that the target's `prototype` property has a
             * method with the given name.
             *
             *     function Cat () {}
             *     Cat.prototype.meow = function () {};
             *     Cat.hiss = function () {};
             *
             *     expect(Cat).itself.to.respondTo('hiss').but.not.respondTo('meow');
             *
             * @name itself
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('itself', function () {
              flag(this, 'itself', true)
            })

            /**
             * ### .satisfy(matcher[, msg])
             *
             * Invokes the given `matcher` function with the target being passed as the
             * first argument, and asserts that the value returned is truthy.
             *
             *     expect(1).to.satisfy(function(num) {
             *       return num > 0;
             *     });
             *
             * Add `.not` earlier in the chain to negate `.satisfy`.
             *
             *     expect(1).to.not.satisfy(function(num) {
             *       return num > 2;
             *     });
             *
             * `.satisfy` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`.
             *
             *     expect(1).to.satisfy(function(num) {
             *       return num > 2;
             *     }, 'nooo why fail??');
             *
             *     expect(1, 'nooo why fail??').to.satisfy(function(num) {
             *       return num > 2;
             *     });
             *
             * The alias `.satisfies` can be used interchangeably with `.satisfy`.
             *
             * @name satisfy
             * @alias satisfies
             * @param {Function} matcher
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function satisfy(matcher, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object')
              var result = matcher(obj)
              this.assert(
                result,
                'expected #{this} to satisfy ' + _.objDisplay(matcher),
                'expected #{this} to not satisfy' + _.objDisplay(matcher),
                flag(this, 'negate') ? false : true,
                result
              )
            }

            Assertion.addMethod('satisfy', satisfy)
            Assertion.addMethod('satisfies', satisfy)

            /**
             * ### .closeTo(expected, delta[, msg])
             *
             * Asserts that the target is a number that's within a given +/- `delta` range
             * of the given number `expected`. However, it's often best to assert that the
             * target is equal to its expected value.
             *
             *     // Recommended
             *     expect(1.5).to.equal(1.5);
             *
             *     // Not recommended
             *     expect(1.5).to.be.closeTo(1, 0.5);
             *     expect(1.5).to.be.closeTo(2, 0.5);
             *     expect(1.5).to.be.closeTo(1, 1);
             *
             * Add `.not` earlier in the chain to negate `.closeTo`.
             *
             *     expect(1.5).to.equal(1.5); // Recommended
             *     expect(1.5).to.not.be.closeTo(3, 1); // Not recommended
             *
             * `.closeTo` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`.
             *
             *     expect(1.5).to.be.closeTo(3, 1, 'nooo why fail??');
             *     expect(1.5, 'nooo why fail??').to.be.closeTo(3, 1);
             *
             * The alias `.approximately` can be used interchangeably with `.closeTo`.
             *
             * @name closeTo
             * @alias approximately
             * @param {Number} expected
             * @param {Number} delta
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function closeTo(expected, delta, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                flagMsg = flag(this, 'message'),
                ssfi = flag(this, 'ssfi')

              new Assertion(obj, flagMsg, ssfi, true).is.a('number')
              if (typeof expected !== 'number' || typeof delta !== 'number') {
                flagMsg = flagMsg ? flagMsg + ': ' : ''
                var deltaMessage =
                  delta === undefined ? ', and a delta is required' : ''
                throw new AssertionError(
                  flagMsg +
                    'the arguments to closeTo or approximately must be numbers' +
                    deltaMessage,
                  undefined,
                  ssfi
                )
              }

              this.assert(
                Math.abs(obj - expected) <= delta,
                'expected #{this} to be close to ' + expected + ' +/- ' + delta,
                'expected #{this} not to be close to ' +
                  expected +
                  ' +/- ' +
                  delta
              )
            }

            Assertion.addMethod('closeTo', closeTo)
            Assertion.addMethod('approximately', closeTo)

            // Note: Duplicates are ignored if testing for inclusion instead of sameness.
            function isSubsetOf(subset, superset, cmp, contains, ordered) {
              if (!contains) {
                if (subset.length !== superset.length) return false
                superset = superset.slice()
              }

              return subset.every(function (elem, idx) {
                if (ordered)
                  return cmp ? cmp(elem, superset[idx]) : elem === superset[idx]

                if (!cmp) {
                  var matchIdx = superset.indexOf(elem)
                  if (matchIdx === -1) return false

                  // Remove match from superset so not counted twice if duplicate in subset.
                  if (!contains) superset.splice(matchIdx, 1)
                  return true
                }

                return superset.some(function (elem2, matchIdx) {
                  if (!cmp(elem, elem2)) return false

                  // Remove match from superset so not counted twice if duplicate in subset.
                  if (!contains) superset.splice(matchIdx, 1)
                  return true
                })
              })
            }

            /**
             * ### .members(set[, msg])
             *
             * Asserts that the target array has the same members as the given array
             * `set`.
             *
             *     expect([1, 2, 3]).to.have.members([2, 1, 3]);
             *     expect([1, 2, 2]).to.have.members([2, 1, 2]);
             *
             * By default, members are compared using strict (`===`) equality. Add `.deep`
             * earlier in the chain to use deep equality instead. See the `deep-eql`
             * project page for info on the deep equality algorithm:
             * https://github.com/chaijs/deep-eql.
             *
             *     // Target array deeply (but not strictly) has member `{a: 1}`
             *     expect([{a: 1}]).to.have.deep.members([{a: 1}]);
             *     expect([{a: 1}]).to.not.have.members([{a: 1}]);
             *
             * By default, order doesn't matter. Add `.ordered` earlier in the chain to
             * require that members appear in the same order.
             *
             *     expect([1, 2, 3]).to.have.ordered.members([1, 2, 3]);
             *     expect([1, 2, 3]).to.have.members([2, 1, 3])
             *       .but.not.ordered.members([2, 1, 3]);
             *
             * By default, both arrays must be the same size. Add `.include` earlier in
             * the chain to require that the target's members be a superset of the
             * expected members. Note that duplicates are ignored in the subset when
             * `.include` is added.
             *
             *     // Target array is a superset of [1, 2] but not identical
             *     expect([1, 2, 3]).to.include.members([1, 2]);
             *     expect([1, 2, 3]).to.not.have.members([1, 2]);
             *
             *     // Duplicates in the subset are ignored
             *     expect([1, 2, 3]).to.include.members([1, 2, 2, 2]);
             *
             * `.deep`, `.ordered`, and `.include` can all be combined. However, if
             * `.include` and `.ordered` are combined, the ordering begins at the start of
             * both arrays.
             *
             *     expect([{a: 1}, {b: 2}, {c: 3}])
             *       .to.include.deep.ordered.members([{a: 1}, {b: 2}])
             *       .but.not.include.deep.ordered.members([{b: 2}, {c: 3}]);
             *
             * Add `.not` earlier in the chain to negate `.members`. However, it's
             * dangerous to do so. The problem is that it creates uncertain expectations
             * by asserting that the target array doesn't have all of the same members as
             * the given array `set` but may or may not have some of them. It's often best
             * to identify the exact output that's expected, and then write an assertion
             * that only accepts that exact output.
             *
             *     expect([1, 2]).to.not.include(3).and.not.include(4); // Recommended
             *     expect([1, 2]).to.not.have.members([3, 4]); // Not recommended
             *
             * `.members` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`.
             *
             *     expect([1, 2]).to.have.members([1, 2, 3], 'nooo why fail??');
             *     expect([1, 2], 'nooo why fail??').to.have.members([1, 2, 3]);
             *
             * @name members
             * @param {Array} set
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            Assertion.addMethod('members', function (subset, msg) {
              if (msg) flag(this, 'message', msg)
              var obj = flag(this, 'object'),
                flagMsg = flag(this, 'message'),
                ssfi = flag(this, 'ssfi')

              new Assertion(obj, flagMsg, ssfi, true).to.be.an('array')
              new Assertion(subset, flagMsg, ssfi, true).to.be.an('array')

              var contains = flag(this, 'contains')
              var ordered = flag(this, 'ordered')

              var subject, failMsg, failNegateMsg

              if (contains) {
                subject = ordered ? 'an ordered superset' : 'a superset'
                failMsg = 'expected #{this} to be ' + subject + ' of #{exp}'
                failNegateMsg =
                  'expected #{this} to not be ' + subject + ' of #{exp}'
              } else {
                subject = ordered ? 'ordered members' : 'members'
                failMsg =
                  'expected #{this} to have the same ' + subject + ' as #{exp}'
                failNegateMsg =
                  'expected #{this} to not have the same ' +
                  subject +
                  ' as #{exp}'
              }

              var cmp = flag(this, 'deep') ? _.eql : undefined

              this.assert(
                isSubsetOf(subset, obj, cmp, contains, ordered),
                failMsg,
                failNegateMsg,
                subset,
                obj,
                true
              )
            })

            /**
             * ### .oneOf(list[, msg])
             *
             * Asserts that the target is a member of the given array `list`. However,
             * it's often best to assert that the target is equal to its expected value.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.be.oneOf([1, 2, 3]); // Not recommended
             *
             * Comparisons are performed using strict (`===`) equality.
             *
             * Add `.not` earlier in the chain to negate `.oneOf`.
             *
             *     expect(1).to.equal(1); // Recommended
             *     expect(1).to.not.be.oneOf([2, 3, 4]); // Not recommended
             *
             * It can also be chained with `.contain` or `.include`, which will work with
             * both arrays and strings:
             *
             *     expect('Today is sunny').to.contain.oneOf(['sunny', 'cloudy'])
             *     expect('Today is rainy').to.not.contain.oneOf(['sunny', 'cloudy'])
             *     expect([1,2,3]).to.contain.oneOf([3,4,5])
             *     expect([1,2,3]).to.not.contain.oneOf([4,5,6])
             *
             * `.oneOf` accepts an optional `msg` argument which is a custom error message
             * to show when the assertion fails. The message can also be given as the
             * second argument to `expect`.
             *
             *     expect(1).to.be.oneOf([2, 3, 4], 'nooo why fail??');
             *     expect(1, 'nooo why fail??').to.be.oneOf([2, 3, 4]);
             *
             * @name oneOf
             * @param {Array<*>} list
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function oneOf(list, msg) {
              if (msg) flag(this, 'message', msg)
              var expected = flag(this, 'object'),
                flagMsg = flag(this, 'message'),
                ssfi = flag(this, 'ssfi'),
                contains = flag(this, 'contains'),
                isDeep = flag(this, 'deep')
              new Assertion(list, flagMsg, ssfi, true).to.be.an('array')

              if (contains) {
                this.assert(
                  list.some(function (possibility) {
                    return expected.indexOf(possibility) > -1
                  }),
                  'expected #{this} to contain one of #{exp}',
                  'expected #{this} to not contain one of #{exp}',
                  list,
                  expected
                )
              } else {
                if (isDeep) {
                  this.assert(
                    list.some(function (possibility) {
                      return _.eql(expected, possibility)
                    }),
                    'expected #{this} to deeply equal one of #{exp}',
                    'expected #{this} to deeply equal one of #{exp}',
                    list,
                    expected
                  )
                } else {
                  this.assert(
                    list.indexOf(expected) > -1,
                    'expected #{this} to be one of #{exp}',
                    'expected #{this} to not be one of #{exp}',
                    list,
                    expected
                  )
                }
              }
            }

            Assertion.addMethod('oneOf', oneOf)

            /**
             * ### .change(subject[, prop[, msg]])
             *
             * When one argument is provided, `.change` asserts that the given function
             * `subject` returns a different value when it's invoked before the target
             * function compared to when it's invoked afterward. However, it's often best
             * to assert that `subject` is equal to its expected value.
             *
             *     var dots = ''
             *       , addDot = function () { dots += '.'; }
             *       , getDots = function () { return dots; };
             *
             *     // Recommended
             *     expect(getDots()).to.equal('');
             *     addDot();
             *     expect(getDots()).to.equal('.');
             *
             *     // Not recommended
             *     expect(addDot).to.change(getDots);
             *
             * When two arguments are provided, `.change` asserts that the value of the
             * given object `subject`'s `prop` property is different before invoking the
             * target function compared to afterward.
             *
             *     var myObj = {dots: ''}
             *       , addDot = function () { myObj.dots += '.'; };
             *
             *     // Recommended
             *     expect(myObj).to.have.property('dots', '');
             *     addDot();
             *     expect(myObj).to.have.property('dots', '.');
             *
             *     // Not recommended
             *     expect(addDot).to.change(myObj, 'dots');
             *
             * Strict (`===`) equality is used to compare before and after values.
             *
             * Add `.not` earlier in the chain to negate `.change`.
             *
             *     var dots = ''
             *       , noop = function () {}
             *       , getDots = function () { return dots; };
             *
             *     expect(noop).to.not.change(getDots);
             *
             *     var myObj = {dots: ''}
             *       , noop = function () {};
             *
             *     expect(noop).to.not.change(myObj, 'dots');
             *
             * `.change` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`. When not providing two arguments, always
             * use the second form.
             *
             *     var myObj = {dots: ''}
             *       , addDot = function () { myObj.dots += '.'; };
             *
             *     expect(addDot).to.not.change(myObj, 'dots', 'nooo why fail??');
             *
             *     var dots = ''
             *       , addDot = function () { dots += '.'; }
             *       , getDots = function () { return dots; };
             *
             *     expect(addDot, 'nooo why fail??').to.not.change(getDots);
             *
             * `.change` also causes all `.by` assertions that follow in the chain to
             * assert how much a numeric subject was increased or decreased by. However,
             * it's dangerous to use `.change.by`. The problem is that it creates
             * uncertain expectations by asserting that the subject either increases by
             * the given delta, or that it decreases by the given delta. It's often best
             * to identify the exact output that's expected, and then write an assertion
             * that only accepts that exact output.
             *
             *     var myObj = {val: 1}
             *       , addTwo = function () { myObj.val += 2; }
             *       , subtractTwo = function () { myObj.val -= 2; };
             *
             *     expect(addTwo).to.increase(myObj, 'val').by(2); // Recommended
             *     expect(addTwo).to.change(myObj, 'val').by(2); // Not recommended
             *
             *     expect(subtractTwo).to.decrease(myObj, 'val').by(2); // Recommended
             *     expect(subtractTwo).to.change(myObj, 'val').by(2); // Not recommended
             *
             * The alias `.changes` can be used interchangeably with `.change`.
             *
             * @name change
             * @alias changes
             * @param {String} subject
             * @param {String} prop name _optional_
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertChanges(subject, prop, msg) {
              if (msg) flag(this, 'message', msg)
              var fn = flag(this, 'object'),
                flagMsg = flag(this, 'message'),
                ssfi = flag(this, 'ssfi')
              new Assertion(fn, flagMsg, ssfi, true).is.a('function')

              var initial
              if (!prop) {
                new Assertion(subject, flagMsg, ssfi, true).is.a('function')
                initial = subject()
              } else {
                new Assertion(subject, flagMsg, ssfi, true).to.have.property(
                  prop
                )
                initial = subject[prop]
              }

              fn()

              var final =
                prop === undefined || prop === null ? subject() : subject[prop]
              var msgObj =
                prop === undefined || prop === null ? initial : '.' + prop

              // This gets flagged because of the .by(delta) assertion
              flag(this, 'deltaMsgObj', msgObj)
              flag(this, 'initialDeltaValue', initial)
              flag(this, 'finalDeltaValue', final)
              flag(this, 'deltaBehavior', 'change')
              flag(this, 'realDelta', final !== initial)

              this.assert(
                initial !== final,
                'expected ' + msgObj + ' to change',
                'expected ' + msgObj + ' to not change'
              )
            }

            Assertion.addMethod('change', assertChanges)
            Assertion.addMethod('changes', assertChanges)

            /**
             * ### .increase(subject[, prop[, msg]])
             *
             * When one argument is provided, `.increase` asserts that the given function
             * `subject` returns a greater number when it's invoked after invoking the
             * target function compared to when it's invoked beforehand. `.increase` also
             * causes all `.by` assertions that follow in the chain to assert how much
             * greater of a number is returned. It's often best to assert that the return
             * value increased by the expected amount, rather than asserting it increased
             * by any amount.
             *
             *     var val = 1
             *       , addTwo = function () { val += 2; }
             *       , getVal = function () { return val; };
             *
             *     expect(addTwo).to.increase(getVal).by(2); // Recommended
             *     expect(addTwo).to.increase(getVal); // Not recommended
             *
             * When two arguments are provided, `.increase` asserts that the value of the
             * given object `subject`'s `prop` property is greater after invoking the
             * target function compared to beforehand.
             *
             *     var myObj = {val: 1}
             *       , addTwo = function () { myObj.val += 2; };
             *
             *     expect(addTwo).to.increase(myObj, 'val').by(2); // Recommended
             *     expect(addTwo).to.increase(myObj, 'val'); // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.increase`. However, it's
             * dangerous to do so. The problem is that it creates uncertain expectations
             * by asserting that the subject either decreases, or that it stays the same.
             * It's often best to identify the exact output that's expected, and then
             * write an assertion that only accepts that exact output.
             *
             * When the subject is expected to decrease, it's often best to assert that it
             * decreased by the expected amount.
             *
             *     var myObj = {val: 1}
             *       , subtractTwo = function () { myObj.val -= 2; };
             *
             *     expect(subtractTwo).to.decrease(myObj, 'val').by(2); // Recommended
             *     expect(subtractTwo).to.not.increase(myObj, 'val'); // Not recommended
             *
             * When the subject is expected to stay the same, it's often best to assert
             * exactly that.
             *
             *     var myObj = {val: 1}
             *       , noop = function () {};
             *
             *     expect(noop).to.not.change(myObj, 'val'); // Recommended
             *     expect(noop).to.not.increase(myObj, 'val'); // Not recommended
             *
             * `.increase` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`. When not providing two arguments, always
             * use the second form.
             *
             *     var myObj = {val: 1}
             *       , noop = function () {};
             *
             *     expect(noop).to.increase(myObj, 'val', 'nooo why fail??');
             *
             *     var val = 1
             *       , noop = function () {}
             *       , getVal = function () { return val; };
             *
             *     expect(noop, 'nooo why fail??').to.increase(getVal);
             *
             * The alias `.increases` can be used interchangeably with `.increase`.
             *
             * @name increase
             * @alias increases
             * @param {String|Function} subject
             * @param {String} prop name _optional_
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertIncreases(subject, prop, msg) {
              if (msg) flag(this, 'message', msg)
              var fn = flag(this, 'object'),
                flagMsg = flag(this, 'message'),
                ssfi = flag(this, 'ssfi')
              new Assertion(fn, flagMsg, ssfi, true).is.a('function')

              var initial
              if (!prop) {
                new Assertion(subject, flagMsg, ssfi, true).is.a('function')
                initial = subject()
              } else {
                new Assertion(subject, flagMsg, ssfi, true).to.have.property(
                  prop
                )
                initial = subject[prop]
              }

              // Make sure that the target is a number
              new Assertion(initial, flagMsg, ssfi, true).is.a('number')

              fn()

              var final =
                prop === undefined || prop === null ? subject() : subject[prop]
              var msgObj =
                prop === undefined || prop === null ? initial : '.' + prop

              flag(this, 'deltaMsgObj', msgObj)
              flag(this, 'initialDeltaValue', initial)
              flag(this, 'finalDeltaValue', final)
              flag(this, 'deltaBehavior', 'increase')
              flag(this, 'realDelta', final - initial)

              this.assert(
                final - initial > 0,
                'expected ' + msgObj + ' to increase',
                'expected ' + msgObj + ' to not increase'
              )
            }

            Assertion.addMethod('increase', assertIncreases)
            Assertion.addMethod('increases', assertIncreases)

            /**
             * ### .decrease(subject[, prop[, msg]])
             *
             * When one argument is provided, `.decrease` asserts that the given function
             * `subject` returns a lesser number when it's invoked after invoking the
             * target function compared to when it's invoked beforehand. `.decrease` also
             * causes all `.by` assertions that follow in the chain to assert how much
             * lesser of a number is returned. It's often best to assert that the return
             * value decreased by the expected amount, rather than asserting it decreased
             * by any amount.
             *
             *     var val = 1
             *       , subtractTwo = function () { val -= 2; }
             *       , getVal = function () { return val; };
             *
             *     expect(subtractTwo).to.decrease(getVal).by(2); // Recommended
             *     expect(subtractTwo).to.decrease(getVal); // Not recommended
             *
             * When two arguments are provided, `.decrease` asserts that the value of the
             * given object `subject`'s `prop` property is lesser after invoking the
             * target function compared to beforehand.
             *
             *     var myObj = {val: 1}
             *       , subtractTwo = function () { myObj.val -= 2; };
             *
             *     expect(subtractTwo).to.decrease(myObj, 'val').by(2); // Recommended
             *     expect(subtractTwo).to.decrease(myObj, 'val'); // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.decrease`. However, it's
             * dangerous to do so. The problem is that it creates uncertain expectations
             * by asserting that the subject either increases, or that it stays the same.
             * It's often best to identify the exact output that's expected, and then
             * write an assertion that only accepts that exact output.
             *
             * When the subject is expected to increase, it's often best to assert that it
             * increased by the expected amount.
             *
             *     var myObj = {val: 1}
             *       , addTwo = function () { myObj.val += 2; };
             *
             *     expect(addTwo).to.increase(myObj, 'val').by(2); // Recommended
             *     expect(addTwo).to.not.decrease(myObj, 'val'); // Not recommended
             *
             * When the subject is expected to stay the same, it's often best to assert
             * exactly that.
             *
             *     var myObj = {val: 1}
             *       , noop = function () {};
             *
             *     expect(noop).to.not.change(myObj, 'val'); // Recommended
             *     expect(noop).to.not.decrease(myObj, 'val'); // Not recommended
             *
             * `.decrease` accepts an optional `msg` argument which is a custom error
             * message to show when the assertion fails. The message can also be given as
             * the second argument to `expect`. When not providing two arguments, always
             * use the second form.
             *
             *     var myObj = {val: 1}
             *       , noop = function () {};
             *
             *     expect(noop).to.decrease(myObj, 'val', 'nooo why fail??');
             *
             *     var val = 1
             *       , noop = function () {}
             *       , getVal = function () { return val; };
             *
             *     expect(noop, 'nooo why fail??').to.decrease(getVal);
             *
             * The alias `.decreases` can be used interchangeably with `.decrease`.
             *
             * @name decrease
             * @alias decreases
             * @param {String|Function} subject
             * @param {String} prop name _optional_
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertDecreases(subject, prop, msg) {
              if (msg) flag(this, 'message', msg)
              var fn = flag(this, 'object'),
                flagMsg = flag(this, 'message'),
                ssfi = flag(this, 'ssfi')
              new Assertion(fn, flagMsg, ssfi, true).is.a('function')

              var initial
              if (!prop) {
                new Assertion(subject, flagMsg, ssfi, true).is.a('function')
                initial = subject()
              } else {
                new Assertion(subject, flagMsg, ssfi, true).to.have.property(
                  prop
                )
                initial = subject[prop]
              }

              // Make sure that the target is a number
              new Assertion(initial, flagMsg, ssfi, true).is.a('number')

              fn()

              var final =
                prop === undefined || prop === null ? subject() : subject[prop]
              var msgObj =
                prop === undefined || prop === null ? initial : '.' + prop

              flag(this, 'deltaMsgObj', msgObj)
              flag(this, 'initialDeltaValue', initial)
              flag(this, 'finalDeltaValue', final)
              flag(this, 'deltaBehavior', 'decrease')
              flag(this, 'realDelta', initial - final)

              this.assert(
                final - initial < 0,
                'expected ' + msgObj + ' to decrease',
                'expected ' + msgObj + ' to not decrease'
              )
            }

            Assertion.addMethod('decrease', assertDecreases)
            Assertion.addMethod('decreases', assertDecreases)

            /**
             * ### .by(delta[, msg])
             *
             * When following an `.increase` assertion in the chain, `.by` asserts that
             * the subject of the `.increase` assertion increased by the given `delta`.
             *
             *     var myObj = {val: 1}
             *       , addTwo = function () { myObj.val += 2; };
             *
             *     expect(addTwo).to.increase(myObj, 'val').by(2);
             *
             * When following a `.decrease` assertion in the chain, `.by` asserts that the
             * subject of the `.decrease` assertion decreased by the given `delta`.
             *
             *     var myObj = {val: 1}
             *       , subtractTwo = function () { myObj.val -= 2; };
             *
             *     expect(subtractTwo).to.decrease(myObj, 'val').by(2);
             *
             * When following a `.change` assertion in the chain, `.by` asserts that the
             * subject of the `.change` assertion either increased or decreased by the
             * given `delta`. However, it's dangerous to use `.change.by`. The problem is
             * that it creates uncertain expectations. It's often best to identify the
             * exact output that's expected, and then write an assertion that only accepts
             * that exact output.
             *
             *     var myObj = {val: 1}
             *       , addTwo = function () { myObj.val += 2; }
             *       , subtractTwo = function () { myObj.val -= 2; };
             *
             *     expect(addTwo).to.increase(myObj, 'val').by(2); // Recommended
             *     expect(addTwo).to.change(myObj, 'val').by(2); // Not recommended
             *
             *     expect(subtractTwo).to.decrease(myObj, 'val').by(2); // Recommended
             *     expect(subtractTwo).to.change(myObj, 'val').by(2); // Not recommended
             *
             * Add `.not` earlier in the chain to negate `.by`. However, it's often best
             * to assert that the subject changed by its expected delta, rather than
             * asserting that it didn't change by one of countless unexpected deltas.
             *
             *     var myObj = {val: 1}
             *       , addTwo = function () { myObj.val += 2; };
             *
             *     // Recommended
             *     expect(addTwo).to.increase(myObj, 'val').by(2);
             *
             *     // Not recommended
             *     expect(addTwo).to.increase(myObj, 'val').but.not.by(3);
             *
             * `.by` accepts an optional `msg` argument which is a custom error message to
             * show when the assertion fails. The message can also be given as the second
             * argument to `expect`.
             *
             *     var myObj = {val: 1}
             *       , addTwo = function () { myObj.val += 2; };
             *
             *     expect(addTwo).to.increase(myObj, 'val').by(3, 'nooo why fail??');
             *     expect(addTwo, 'nooo why fail??').to.increase(myObj, 'val').by(3);
             *
             * @name by
             * @param {Number} delta
             * @param {String} msg _optional_
             * @namespace BDD
             * @api public
             */

            function assertDelta(delta, msg) {
              if (msg) flag(this, 'message', msg)

              var msgObj = flag(this, 'deltaMsgObj')
              var initial = flag(this, 'initialDeltaValue')
              var final = flag(this, 'finalDeltaValue')
              var behavior = flag(this, 'deltaBehavior')
              var realDelta = flag(this, 'realDelta')

              var expression
              if (behavior === 'change') {
                expression = Math.abs(final - initial) === Math.abs(delta)
              } else {
                expression = realDelta === Math.abs(delta)
              }

              this.assert(
                expression,
                'expected ' + msgObj + ' to ' + behavior + ' by ' + delta,
                'expected ' + msgObj + ' to not ' + behavior + ' by ' + delta
              )
            }

            Assertion.addMethod('by', assertDelta)

            /**
             * ### .extensible
             *
             * Asserts that the target is extensible, which means that new properties can
             * be added to it. Primitives are never extensible.
             *
             *     expect({a: 1}).to.be.extensible;
             *
             * Add `.not` earlier in the chain to negate `.extensible`.
             *
             *     var nonExtensibleObject = Object.preventExtensions({})
             *       , sealedObject = Object.seal({})
             *       , frozenObject = Object.freeze({});
             *
             *     expect(nonExtensibleObject).to.not.be.extensible;
             *     expect(sealedObject).to.not.be.extensible;
             *     expect(frozenObject).to.not.be.extensible;
             *     expect(1).to.not.be.extensible;
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect(1, 'nooo why fail??').to.be.extensible;
             *
             * @name extensible
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('extensible', function () {
              var obj = flag(this, 'object')

              // In ES5, if the argument to this method is a primitive, then it will cause a TypeError.
              // In ES6, a non-object argument will be treated as if it was a non-extensible ordinary object, simply return false.
              // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/isExtensible
              // The following provides ES6 behavior for ES5 environments.

              var isExtensible = obj === Object(obj) && Object.isExtensible(obj)

              this.assert(
                isExtensible,
                'expected #{this} to be extensible',
                'expected #{this} to not be extensible'
              )
            })

            /**
             * ### .sealed
             *
             * Asserts that the target is sealed, which means that new properties can't be
             * added to it, and its existing properties can't be reconfigured or deleted.
             * However, it's possible that its existing properties can still be reassigned
             * to different values. Primitives are always sealed.
             *
             *     var sealedObject = Object.seal({});
             *     var frozenObject = Object.freeze({});
             *
             *     expect(sealedObject).to.be.sealed;
             *     expect(frozenObject).to.be.sealed;
             *     expect(1).to.be.sealed;
             *
             * Add `.not` earlier in the chain to negate `.sealed`.
             *
             *     expect({a: 1}).to.not.be.sealed;
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect({a: 1}, 'nooo why fail??').to.be.sealed;
             *
             * @name sealed
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('sealed', function () {
              var obj = flag(this, 'object')

              // In ES5, if the argument to this method is a primitive, then it will cause a TypeError.
              // In ES6, a non-object argument will be treated as if it was a sealed ordinary object, simply return true.
              // See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/isSealed
              // The following provides ES6 behavior for ES5 environments.

              var isSealed = obj === Object(obj) ? Object.isSealed(obj) : true

              this.assert(
                isSealed,
                'expected #{this} to be sealed',
                'expected #{this} to not be sealed'
              )
            })

            /**
             * ### .frozen
             *
             * Asserts that the target is frozen, which means that new properties can't be
             * added to it, and its existing properties can't be reassigned to different
             * values, reconfigured, or deleted. Primitives are always frozen.
             *
             *     var frozenObject = Object.freeze({});
             *
             *     expect(frozenObject).to.be.frozen;
             *     expect(1).to.be.frozen;
             *
             * Add `.not` earlier in the chain to negate `.frozen`.
             *
             *     expect({a: 1}).to.not.be.frozen;
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect({a: 1}, 'nooo why fail??').to.be.frozen;
             *
             * @name frozen
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('frozen', function () {
              var obj = flag(this, 'object')

              // In ES5, if the argument to this method is a primitive, then it will cause a TypeError.
              // In ES6, a non-object argument will be treated as if it was a frozen ordinary object, simply return true.
              // See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/isFrozen
              // The following provides ES6 behavior for ES5 environments.

              var isFrozen = obj === Object(obj) ? Object.isFrozen(obj) : true

              this.assert(
                isFrozen,
                'expected #{this} to be frozen',
                'expected #{this} to not be frozen'
              )
            })

            /**
             * ### .finite
             *
             * Asserts that the target is a number, and isn't `NaN` or positive/negative
             * `Infinity`.
             *
             *     expect(1).to.be.finite;
             *
             * Add `.not` earlier in the chain to negate `.finite`. However, it's
             * dangerous to do so. The problem is that it creates uncertain expectations
             * by asserting that the subject either isn't a number, or that it's `NaN`, or
             * that it's positive `Infinity`, or that it's negative `Infinity`. It's often
             * best to identify the exact output that's expected, and then write an
             * assertion that only accepts that exact output.
             *
             * When the target isn't expected to be a number, it's often best to assert
             * that it's the expected type, rather than asserting that it isn't one of
             * many unexpected types.
             *
             *     expect('foo').to.be.a('string'); // Recommended
             *     expect('foo').to.not.be.finite; // Not recommended
             *
             * When the target is expected to be `NaN`, it's often best to assert exactly
             * that.
             *
             *     expect(NaN).to.be.NaN; // Recommended
             *     expect(NaN).to.not.be.finite; // Not recommended
             *
             * When the target is expected to be positive infinity, it's often best to
             * assert exactly that.
             *
             *     expect(Infinity).to.equal(Infinity); // Recommended
             *     expect(Infinity).to.not.be.finite; // Not recommended
             *
             * When the target is expected to be negative infinity, it's often best to
             * assert exactly that.
             *
             *     expect(-Infinity).to.equal(-Infinity); // Recommended
             *     expect(-Infinity).to.not.be.finite; // Not recommended
             *
             * A custom error message can be given as the second argument to `expect`.
             *
             *     expect('foo', 'nooo why fail??').to.be.finite;
             *
             * @name finite
             * @namespace BDD
             * @api public
             */

            Assertion.addProperty('finite', function (msg) {
              var obj = flag(this, 'object')

              this.assert(
                typeof obj === 'number' && isFinite(obj),
                'expected #{this} to be a finite number',
                'expected #{this} to not be a finite number'
              )
            })
          }
        },
        {}
      ],
      6: [
        function (require, module, exports) {
          /*!
           * chai
           * Copyright(c) 2011-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          module.exports = function (chai, util) {
            /*!
             * Chai dependencies.
             */

            var Assertion = chai.Assertion,
              flag = util.flag

            /*!
             * Module export.
             */

            /**
             * ### assert(expression, message)
             *
             * Write your own test expressions.
             *
             *     assert('foo' !== 'bar', 'foo is not bar');
             *     assert(Array.isArray([]), 'empty arrays are arrays');
             *
             * @param {Mixed} expression to test for truthiness
             * @param {String} message to display on error
             * @name assert
             * @namespace Assert
             * @api public
             */

            var assert = (chai.assert = function (express, errmsg) {
              var test = new Assertion(null, null, chai.assert, true)
              test.assert(express, errmsg, '[ negation message unavailable ]')
            })

            /**
             * ### .fail([message])
             * ### .fail(actual, expected, [message], [operator])
             *
             * Throw a failure. Node.js `assert` module-compatible.
             *
             *     assert.fail();
             *     assert.fail("custom error message");
             *     assert.fail(1, 2);
             *     assert.fail(1, 2, "custom error message");
             *     assert.fail(1, 2, "custom error message", ">");
             *     assert.fail(1, 2, undefined, ">");
             *
             * @name fail
             * @param {Mixed} actual
             * @param {Mixed} expected
             * @param {String} message
             * @param {String} operator
             * @namespace Assert
             * @api public
             */

            assert.fail = function (actual, expected, message, operator) {
              if (arguments.length < 2) {
                // Comply with Node's fail([message]) interface

                message = actual
                actual = undefined
              }

              message = message || 'assert.fail()'
              throw new chai.AssertionError(
                message,
                {
                  actual: actual,
                  expected: expected,
                  operator: operator
                },
                assert.fail
              )
            }

            /**
             * ### .isOk(object, [message])
             *
             * Asserts that `object` is truthy.
             *
             *     assert.isOk('everything', 'everything is ok');
             *     assert.isOk(false, 'this will fail');
             *
             * @name isOk
             * @alias ok
             * @param {Mixed} object to test
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isOk = function (val, msg) {
              new Assertion(val, msg, assert.isOk, true).is.ok
            }

            /**
             * ### .isNotOk(object, [message])
             *
             * Asserts that `object` is falsy.
             *
             *     assert.isNotOk('everything', 'this will fail');
             *     assert.isNotOk(false, 'this will pass');
             *
             * @name isNotOk
             * @alias notOk
             * @param {Mixed} object to test
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotOk = function (val, msg) {
              new Assertion(val, msg, assert.isNotOk, true).is.not.ok
            }

            /**
             * ### .equal(actual, expected, [message])
             *
             * Asserts non-strict equality (`==`) of `actual` and `expected`.
             *
             *     assert.equal(3, '3', '== coerces values to strings');
             *
             * @name equal
             * @param {Mixed} actual
             * @param {Mixed} expected
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.equal = function (act, exp, msg) {
              var test = new Assertion(act, msg, assert.equal, true)

              test.assert(
                exp == flag(test, 'object'),
                'expected #{this} to equal #{exp}',
                'expected #{this} to not equal #{act}',
                exp,
                act,
                true
              )
            }

            /**
             * ### .notEqual(actual, expected, [message])
             *
             * Asserts non-strict inequality (`!=`) of `actual` and `expected`.
             *
             *     assert.notEqual(3, 4, 'these numbers are not equal');
             *
             * @name notEqual
             * @param {Mixed} actual
             * @param {Mixed} expected
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notEqual = function (act, exp, msg) {
              var test = new Assertion(act, msg, assert.notEqual, true)

              test.assert(
                exp != flag(test, 'object'),
                'expected #{this} to not equal #{exp}',
                'expected #{this} to equal #{act}',
                exp,
                act,
                true
              )
            }

            /**
             * ### .strictEqual(actual, expected, [message])
             *
             * Asserts strict equality (`===`) of `actual` and `expected`.
             *
             *     assert.strictEqual(true, true, 'these booleans are strictly equal');
             *
             * @name strictEqual
             * @param {Mixed} actual
             * @param {Mixed} expected
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.strictEqual = function (act, exp, msg) {
              new Assertion(act, msg, assert.strictEqual, true).to.equal(exp)
            }

            /**
             * ### .notStrictEqual(actual, expected, [message])
             *
             * Asserts strict inequality (`!==`) of `actual` and `expected`.
             *
             *     assert.notStrictEqual(3, '3', 'no coercion for strict equality');
             *
             * @name notStrictEqual
             * @param {Mixed} actual
             * @param {Mixed} expected
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notStrictEqual = function (act, exp, msg) {
              new Assertion(act, msg, assert.notStrictEqual, true).to.not.equal(
                exp
              )
            }

            /**
             * ### .deepEqual(actual, expected, [message])
             *
             * Asserts that `actual` is deeply equal to `expected`.
             *
             *     assert.deepEqual({ tea: 'green' }, { tea: 'green' });
             *
             * @name deepEqual
             * @param {Mixed} actual
             * @param {Mixed} expected
             * @param {String} message
             * @alias deepStrictEqual
             * @namespace Assert
             * @api public
             */

            assert.deepEqual = assert.deepStrictEqual = function (
              act,
              exp,
              msg
            ) {
              new Assertion(act, msg, assert.deepEqual, true).to.eql(exp)
            }

            /**
             * ### .notDeepEqual(actual, expected, [message])
             *
             * Assert that `actual` is not deeply equal to `expected`.
             *
             *     assert.notDeepEqual({ tea: 'green' }, { tea: 'jasmine' });
             *
             * @name notDeepEqual
             * @param {Mixed} actual
             * @param {Mixed} expected
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notDeepEqual = function (act, exp, msg) {
              new Assertion(act, msg, assert.notDeepEqual, true).to.not.eql(exp)
            }

            /**
             * ### .isAbove(valueToCheck, valueToBeAbove, [message])
             *
             * Asserts `valueToCheck` is strictly greater than (>) `valueToBeAbove`.
             *
             *     assert.isAbove(5, 2, '5 is strictly greater than 2');
             *
             * @name isAbove
             * @param {Mixed} valueToCheck
             * @param {Mixed} valueToBeAbove
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isAbove = function (val, abv, msg) {
              new Assertion(val, msg, assert.isAbove, true).to.be.above(abv)
            }

            /**
             * ### .isAtLeast(valueToCheck, valueToBeAtLeast, [message])
             *
             * Asserts `valueToCheck` is greater than or equal to (>=) `valueToBeAtLeast`.
             *
             *     assert.isAtLeast(5, 2, '5 is greater or equal to 2');
             *     assert.isAtLeast(3, 3, '3 is greater or equal to 3');
             *
             * @name isAtLeast
             * @param {Mixed} valueToCheck
             * @param {Mixed} valueToBeAtLeast
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isAtLeast = function (val, atlst, msg) {
              new Assertion(val, msg, assert.isAtLeast, true).to.be.least(atlst)
            }

            /**
             * ### .isBelow(valueToCheck, valueToBeBelow, [message])
             *
             * Asserts `valueToCheck` is strictly less than (<) `valueToBeBelow`.
             *
             *     assert.isBelow(3, 6, '3 is strictly less than 6');
             *
             * @name isBelow
             * @param {Mixed} valueToCheck
             * @param {Mixed} valueToBeBelow
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isBelow = function (val, blw, msg) {
              new Assertion(val, msg, assert.isBelow, true).to.be.below(blw)
            }

            /**
             * ### .isAtMost(valueToCheck, valueToBeAtMost, [message])
             *
             * Asserts `valueToCheck` is less than or equal to (<=) `valueToBeAtMost`.
             *
             *     assert.isAtMost(3, 6, '3 is less than or equal to 6');
             *     assert.isAtMost(4, 4, '4 is less than or equal to 4');
             *
             * @name isAtMost
             * @param {Mixed} valueToCheck
             * @param {Mixed} valueToBeAtMost
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isAtMost = function (val, atmst, msg) {
              new Assertion(val, msg, assert.isAtMost, true).to.be.most(atmst)
            }

            /**
             * ### .isTrue(value, [message])
             *
             * Asserts that `value` is true.
             *
             *     var teaServed = true;
             *     assert.isTrue(teaServed, 'the tea has been served');
             *
             * @name isTrue
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isTrue = function (val, msg) {
              new Assertion(val, msg, assert.isTrue, true).is['true']
            }

            /**
             * ### .isNotTrue(value, [message])
             *
             * Asserts that `value` is not true.
             *
             *     var tea = 'tasty chai';
             *     assert.isNotTrue(tea, 'great, time for tea!');
             *
             * @name isNotTrue
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotTrue = function (val, msg) {
              new Assertion(val, msg, assert.isNotTrue, true).to.not.equal(true)
            }

            /**
             * ### .isFalse(value, [message])
             *
             * Asserts that `value` is false.
             *
             *     var teaServed = false;
             *     assert.isFalse(teaServed, 'no tea yet? hmm...');
             *
             * @name isFalse
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isFalse = function (val, msg) {
              new Assertion(val, msg, assert.isFalse, true).is['false']
            }

            /**
             * ### .isNotFalse(value, [message])
             *
             * Asserts that `value` is not false.
             *
             *     var tea = 'tasty chai';
             *     assert.isNotFalse(tea, 'great, time for tea!');
             *
             * @name isNotFalse
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotFalse = function (val, msg) {
              new Assertion(val, msg, assert.isNotFalse, true).to.not.equal(
                false
              )
            }

            /**
             * ### .isNull(value, [message])
             *
             * Asserts that `value` is null.
             *
             *     assert.isNull(err, 'there was no error');
             *
             * @name isNull
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNull = function (val, msg) {
              new Assertion(val, msg, assert.isNull, true).to.equal(null)
            }

            /**
             * ### .isNotNull(value, [message])
             *
             * Asserts that `value` is not null.
             *
             *     var tea = 'tasty chai';
             *     assert.isNotNull(tea, 'great, time for tea!');
             *
             * @name isNotNull
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotNull = function (val, msg) {
              new Assertion(val, msg, assert.isNotNull, true).to.not.equal(null)
            }

            /**
             * ### .isNaN
             *
             * Asserts that value is NaN.
             *
             *     assert.isNaN(NaN, 'NaN is NaN');
             *
             * @name isNaN
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNaN = function (val, msg) {
              new Assertion(val, msg, assert.isNaN, true).to.be.NaN
            }

            /**
             * ### .isNotNaN
             *
             * Asserts that value is not NaN.
             *
             *     assert.isNotNaN(4, '4 is not NaN');
             *
             * @name isNotNaN
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */
            assert.isNotNaN = function (val, msg) {
              new Assertion(val, msg, assert.isNotNaN, true).not.to.be.NaN
            }

            /**
             * ### .exists
             *
             * Asserts that the target is neither `null` nor `undefined`.
             *
             *     var foo = 'hi';
             *
             *     assert.exists(foo, 'foo is neither `null` nor `undefined`');
             *
             * @name exists
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.exists = function (val, msg) {
              new Assertion(val, msg, assert.exists, true).to.exist
            }

            /**
             * ### .notExists
             *
             * Asserts that the target is either `null` or `undefined`.
             *
             *     var bar = null
             *       , baz;
             *
             *     assert.notExists(bar);
             *     assert.notExists(baz, 'baz is either null or undefined');
             *
             * @name notExists
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notExists = function (val, msg) {
              new Assertion(val, msg, assert.notExists, true).to.not.exist
            }

            /**
             * ### .isUndefined(value, [message])
             *
             * Asserts that `value` is `undefined`.
             *
             *     var tea;
             *     assert.isUndefined(tea, 'no tea defined');
             *
             * @name isUndefined
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isUndefined = function (val, msg) {
              new Assertion(val, msg, assert.isUndefined, true).to.equal(
                undefined
              )
            }

            /**
             * ### .isDefined(value, [message])
             *
             * Asserts that `value` is not `undefined`.
             *
             *     var tea = 'cup of chai';
             *     assert.isDefined(tea, 'tea has been defined');
             *
             * @name isDefined
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isDefined = function (val, msg) {
              new Assertion(val, msg, assert.isDefined, true).to.not.equal(
                undefined
              )
            }

            /**
             * ### .isFunction(value, [message])
             *
             * Asserts that `value` is a function.
             *
             *     function serveTea() { return 'cup of tea'; };
             *     assert.isFunction(serveTea, 'great, we can have tea now');
             *
             * @name isFunction
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isFunction = function (val, msg) {
              new Assertion(val, msg, assert.isFunction, true).to.be.a(
                'function'
              )
            }

            /**
             * ### .isNotFunction(value, [message])
             *
             * Asserts that `value` is _not_ a function.
             *
             *     var serveTea = [ 'heat', 'pour', 'sip' ];
             *     assert.isNotFunction(serveTea, 'great, we have listed the steps');
             *
             * @name isNotFunction
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotFunction = function (val, msg) {
              new Assertion(val, msg, assert.isNotFunction, true).to.not.be.a(
                'function'
              )
            }

            /**
             * ### .isObject(value, [message])
             *
             * Asserts that `value` is an object of type 'Object' (as revealed by `Object.prototype.toString`).
             * _The assertion does not match subclassed objects._
             *
             *     var selection = { name: 'Chai', serve: 'with spices' };
             *     assert.isObject(selection, 'tea selection is an object');
             *
             * @name isObject
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isObject = function (val, msg) {
              new Assertion(val, msg, assert.isObject, true).to.be.a('object')
            }

            /**
             * ### .isNotObject(value, [message])
             *
             * Asserts that `value` is _not_ an object of type 'Object' (as revealed by `Object.prototype.toString`).
             *
             *     var selection = 'chai'
             *     assert.isNotObject(selection, 'tea selection is not an object');
             *     assert.isNotObject(null, 'null is not an object');
             *
             * @name isNotObject
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotObject = function (val, msg) {
              new Assertion(val, msg, assert.isNotObject, true).to.not.be.a(
                'object'
              )
            }

            /**
             * ### .isArray(value, [message])
             *
             * Asserts that `value` is an array.
             *
             *     var menu = [ 'green', 'chai', 'oolong' ];
             *     assert.isArray(menu, 'what kind of tea do we want?');
             *
             * @name isArray
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isArray = function (val, msg) {
              new Assertion(val, msg, assert.isArray, true).to.be.an('array')
            }

            /**
             * ### .isNotArray(value, [message])
             *
             * Asserts that `value` is _not_ an array.
             *
             *     var menu = 'green|chai|oolong';
             *     assert.isNotArray(menu, 'what kind of tea do we want?');
             *
             * @name isNotArray
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotArray = function (val, msg) {
              new Assertion(val, msg, assert.isNotArray, true).to.not.be.an(
                'array'
              )
            }

            /**
             * ### .isString(value, [message])
             *
             * Asserts that `value` is a string.
             *
             *     var teaOrder = 'chai';
             *     assert.isString(teaOrder, 'order placed');
             *
             * @name isString
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isString = function (val, msg) {
              new Assertion(val, msg, assert.isString, true).to.be.a('string')
            }

            /**
             * ### .isNotString(value, [message])
             *
             * Asserts that `value` is _not_ a string.
             *
             *     var teaOrder = 4;
             *     assert.isNotString(teaOrder, 'order placed');
             *
             * @name isNotString
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotString = function (val, msg) {
              new Assertion(val, msg, assert.isNotString, true).to.not.be.a(
                'string'
              )
            }

            /**
             * ### .isNumber(value, [message])
             *
             * Asserts that `value` is a number.
             *
             *     var cups = 2;
             *     assert.isNumber(cups, 'how many cups');
             *
             * @name isNumber
             * @param {Number} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNumber = function (val, msg) {
              new Assertion(val, msg, assert.isNumber, true).to.be.a('number')
            }

            /**
             * ### .isNotNumber(value, [message])
             *
             * Asserts that `value` is _not_ a number.
             *
             *     var cups = '2 cups please';
             *     assert.isNotNumber(cups, 'how many cups');
             *
             * @name isNotNumber
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotNumber = function (val, msg) {
              new Assertion(val, msg, assert.isNotNumber, true).to.not.be.a(
                'number'
              )
            }

            /**
             * ### .isFinite(value, [message])
             *
             * Asserts that `value` is a finite number. Unlike `.isNumber`, this will fail for `NaN` and `Infinity`.
             *
             *     var cups = 2;
             *     assert.isFinite(cups, 'how many cups');
             *
             *     assert.isFinite(NaN); // throws
             *
             * @name isFinite
             * @param {Number} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isFinite = function (val, msg) {
              new Assertion(val, msg, assert.isFinite, true).to.be.finite
            }

            /**
             * ### .isBoolean(value, [message])
             *
             * Asserts that `value` is a boolean.
             *
             *     var teaReady = true
             *       , teaServed = false;
             *
             *     assert.isBoolean(teaReady, 'is the tea ready');
             *     assert.isBoolean(teaServed, 'has tea been served');
             *
             * @name isBoolean
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isBoolean = function (val, msg) {
              new Assertion(val, msg, assert.isBoolean, true).to.be.a('boolean')
            }

            /**
             * ### .isNotBoolean(value, [message])
             *
             * Asserts that `value` is _not_ a boolean.
             *
             *     var teaReady = 'yep'
             *       , teaServed = 'nope';
             *
             *     assert.isNotBoolean(teaReady, 'is the tea ready');
             *     assert.isNotBoolean(teaServed, 'has tea been served');
             *
             * @name isNotBoolean
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.isNotBoolean = function (val, msg) {
              new Assertion(val, msg, assert.isNotBoolean, true).to.not.be.a(
                'boolean'
              )
            }

            /**
             * ### .typeOf(value, name, [message])
             *
             * Asserts that `value`'s type is `name`, as determined by
             * `Object.prototype.toString`.
             *
             *     assert.typeOf({ tea: 'chai' }, 'object', 'we have an object');
             *     assert.typeOf(['chai', 'jasmine'], 'array', 'we have an array');
             *     assert.typeOf('tea', 'string', 'we have a string');
             *     assert.typeOf(/tea/, 'regexp', 'we have a regular expression');
             *     assert.typeOf(null, 'null', 'we have a null');
             *     assert.typeOf(undefined, 'undefined', 'we have an undefined');
             *
             * @name typeOf
             * @param {Mixed} value
             * @param {String} name
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.typeOf = function (val, type, msg) {
              new Assertion(val, msg, assert.typeOf, true).to.be.a(type)
            }

            /**
             * ### .notTypeOf(value, name, [message])
             *
             * Asserts that `value`'s type is _not_ `name`, as determined by
             * `Object.prototype.toString`.
             *
             *     assert.notTypeOf('tea', 'number', 'strings are not numbers');
             *
             * @name notTypeOf
             * @param {Mixed} value
             * @param {String} typeof name
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notTypeOf = function (val, type, msg) {
              new Assertion(val, msg, assert.notTypeOf, true).to.not.be.a(type)
            }

            /**
             * ### .instanceOf(object, constructor, [message])
             *
             * Asserts that `value` is an instance of `constructor`.
             *
             *     var Tea = function (name) { this.name = name; }
             *       , chai = new Tea('chai');
             *
             *     assert.instanceOf(chai, Tea, 'chai is an instance of tea');
             *
             * @name instanceOf
             * @param {Object} object
             * @param {Constructor} constructor
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.instanceOf = function (val, type, msg) {
              new Assertion(val, msg, assert.instanceOf, true).to.be.instanceOf(
                type
              )
            }

            /**
             * ### .notInstanceOf(object, constructor, [message])
             *
             * Asserts `value` is not an instance of `constructor`.
             *
             *     var Tea = function (name) { this.name = name; }
             *       , chai = new String('chai');
             *
             *     assert.notInstanceOf(chai, Tea, 'chai is not an instance of tea');
             *
             * @name notInstanceOf
             * @param {Object} object
             * @param {Constructor} constructor
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notInstanceOf = function (val, type, msg) {
              new Assertion(
                val,
                msg,
                assert.notInstanceOf,
                true
              ).to.not.be.instanceOf(type)
            }

            /**
             * ### .include(haystack, needle, [message])
             *
             * Asserts that `haystack` includes `needle`. Can be used to assert the
             * inclusion of a value in an array, a substring in a string, or a subset of
             * properties in an object.
             *
             *     assert.include([1,2,3], 2, 'array contains value');
             *     assert.include('foobar', 'foo', 'string contains substring');
             *     assert.include({ foo: 'bar', hello: 'universe' }, { foo: 'bar' }, 'object contains property');
             *
             * Strict equality (===) is used. When asserting the inclusion of a value in
             * an array, the array is searched for an element that's strictly equal to the
             * given value. When asserting a subset of properties in an object, the object
             * is searched for the given property keys, checking that each one is present
             * and strictly equal to the given property value. For instance:
             *
             *     var obj1 = {a: 1}
             *       , obj2 = {b: 2};
             *     assert.include([obj1, obj2], obj1);
             *     assert.include({foo: obj1, bar: obj2}, {foo: obj1});
             *     assert.include({foo: obj1, bar: obj2}, {foo: obj1, bar: obj2});
             *
             * @name include
             * @param {Array|String} haystack
             * @param {Mixed} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.include = function (exp, inc, msg) {
              new Assertion(exp, msg, assert.include, true).include(inc)
            }

            /**
             * ### .notInclude(haystack, needle, [message])
             *
             * Asserts that `haystack` does not include `needle`. Can be used to assert
             * the absence of a value in an array, a substring in a string, or a subset of
             * properties in an object.
             *
             *     assert.notInclude([1,2,3], 4, "array doesn't contain value");
             *     assert.notInclude('foobar', 'baz', "string doesn't contain substring");
             *     assert.notInclude({ foo: 'bar', hello: 'universe' }, { foo: 'baz' }, 'object doesn't contain property');
             *
             * Strict equality (===) is used. When asserting the absence of a value in an
             * array, the array is searched to confirm the absence of an element that's
             * strictly equal to the given value. When asserting a subset of properties in
             * an object, the object is searched to confirm that at least one of the given
             * property keys is either not present or not strictly equal to the given
             * property value. For instance:
             *
             *     var obj1 = {a: 1}
             *       , obj2 = {b: 2};
             *     assert.notInclude([obj1, obj2], {a: 1});
             *     assert.notInclude({foo: obj1, bar: obj2}, {foo: {a: 1}});
             *     assert.notInclude({foo: obj1, bar: obj2}, {foo: obj1, bar: {b: 2}});
             *
             * @name notInclude
             * @param {Array|String} haystack
             * @param {Mixed} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notInclude = function (exp, inc, msg) {
              new Assertion(exp, msg, assert.notInclude, true).not.include(inc)
            }

            /**
             * ### .deepInclude(haystack, needle, [message])
             *
             * Asserts that `haystack` includes `needle`. Can be used to assert the
             * inclusion of a value in an array or a subset of properties in an object.
             * Deep equality is used.
             *
             *     var obj1 = {a: 1}
             *       , obj2 = {b: 2};
             *     assert.deepInclude([obj1, obj2], {a: 1});
             *     assert.deepInclude({foo: obj1, bar: obj2}, {foo: {a: 1}});
             *     assert.deepInclude({foo: obj1, bar: obj2}, {foo: {a: 1}, bar: {b: 2}});
             *
             * @name deepInclude
             * @param {Array|String} haystack
             * @param {Mixed} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.deepInclude = function (exp, inc, msg) {
              new Assertion(exp, msg, assert.deepInclude, true).deep.include(
                inc
              )
            }

            /**
             * ### .notDeepInclude(haystack, needle, [message])
             *
             * Asserts that `haystack` does not include `needle`. Can be used to assert
             * the absence of a value in an array or a subset of properties in an object.
             * Deep equality is used.
             *
             *     var obj1 = {a: 1}
             *       , obj2 = {b: 2};
             *     assert.notDeepInclude([obj1, obj2], {a: 9});
             *     assert.notDeepInclude({foo: obj1, bar: obj2}, {foo: {a: 9}});
             *     assert.notDeepInclude({foo: obj1, bar: obj2}, {foo: {a: 1}, bar: {b: 9}});
             *
             * @name notDeepInclude
             * @param {Array|String} haystack
             * @param {Mixed} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notDeepInclude = function (exp, inc, msg) {
              new Assertion(
                exp,
                msg,
                assert.notDeepInclude,
                true
              ).not.deep.include(inc)
            }

            /**
             * ### .nestedInclude(haystack, needle, [message])
             *
             * Asserts that 'haystack' includes 'needle'.
             * Can be used to assert the inclusion of a subset of properties in an
             * object.
             * Enables the use of dot- and bracket-notation for referencing nested
             * properties.
             * '[]' and '.' in property names can be escaped using double backslashes.
             *
             *     assert.nestedInclude({'.a': {'b': 'x'}}, {'\\.a.[b]': 'x'});
             *     assert.nestedInclude({'a': {'[b]': 'x'}}, {'a.\\[b\\]': 'x'});
             *
             * @name nestedInclude
             * @param {Object} haystack
             * @param {Object} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.nestedInclude = function (exp, inc, msg) {
              new Assertion(
                exp,
                msg,
                assert.nestedInclude,
                true
              ).nested.include(inc)
            }

            /**
             * ### .notNestedInclude(haystack, needle, [message])
             *
             * Asserts that 'haystack' does not include 'needle'.
             * Can be used to assert the absence of a subset of properties in an
             * object.
             * Enables the use of dot- and bracket-notation for referencing nested
             * properties.
             * '[]' and '.' in property names can be escaped using double backslashes.
             *
             *     assert.notNestedInclude({'.a': {'b': 'x'}}, {'\\.a.b': 'y'});
             *     assert.notNestedInclude({'a': {'[b]': 'x'}}, {'a.\\[b\\]': 'y'});
             *
             * @name notNestedInclude
             * @param {Object} haystack
             * @param {Object} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notNestedInclude = function (exp, inc, msg) {
              new Assertion(
                exp,
                msg,
                assert.notNestedInclude,
                true
              ).not.nested.include(inc)
            }

            /**
             * ### .deepNestedInclude(haystack, needle, [message])
             *
             * Asserts that 'haystack' includes 'needle'.
             * Can be used to assert the inclusion of a subset of properties in an
             * object while checking for deep equality.
             * Enables the use of dot- and bracket-notation for referencing nested
             * properties.
             * '[]' and '.' in property names can be escaped using double backslashes.
             *
             *     assert.deepNestedInclude({a: {b: [{x: 1}]}}, {'a.b[0]': {x: 1}});
             *     assert.deepNestedInclude({'.a': {'[b]': {x: 1}}}, {'\\.a.\\[b\\]': {x: 1}});
             *
             * @name deepNestedInclude
             * @param {Object} haystack
             * @param {Object} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.deepNestedInclude = function (exp, inc, msg) {
              new Assertion(
                exp,
                msg,
                assert.deepNestedInclude,
                true
              ).deep.nested.include(inc)
            }

            /**
             * ### .notDeepNestedInclude(haystack, needle, [message])
             *
             * Asserts that 'haystack' does not include 'needle'.
             * Can be used to assert the absence of a subset of properties in an
             * object while checking for deep equality.
             * Enables the use of dot- and bracket-notation for referencing nested
             * properties.
             * '[]' and '.' in property names can be escaped using double backslashes.
             *
             *     assert.notDeepNestedInclude({a: {b: [{x: 1}]}}, {'a.b[0]': {y: 1}})
             *     assert.notDeepNestedInclude({'.a': {'[b]': {x: 1}}}, {'\\.a.\\[b\\]': {y: 2}});
             *
             * @name notDeepNestedInclude
             * @param {Object} haystack
             * @param {Object} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notDeepNestedInclude = function (exp, inc, msg) {
              new Assertion(
                exp,
                msg,
                assert.notDeepNestedInclude,
                true
              ).not.deep.nested.include(inc)
            }

            /**
             * ### .ownInclude(haystack, needle, [message])
             *
             * Asserts that 'haystack' includes 'needle'.
             * Can be used to assert the inclusion of a subset of properties in an
             * object while ignoring inherited properties.
             *
             *     assert.ownInclude({ a: 1 }, { a: 1 });
             *
             * @name ownInclude
             * @param {Object} haystack
             * @param {Object} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.ownInclude = function (exp, inc, msg) {
              new Assertion(exp, msg, assert.ownInclude, true).own.include(inc)
            }

            /**
             * ### .notOwnInclude(haystack, needle, [message])
             *
             * Asserts that 'haystack' includes 'needle'.
             * Can be used to assert the absence of a subset of properties in an
             * object while ignoring inherited properties.
             *
             *     Object.prototype.b = 2;
             *
             *     assert.notOwnInclude({ a: 1 }, { b: 2 });
             *
             * @name notOwnInclude
             * @param {Object} haystack
             * @param {Object} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notOwnInclude = function (exp, inc, msg) {
              new Assertion(
                exp,
                msg,
                assert.notOwnInclude,
                true
              ).not.own.include(inc)
            }

            /**
             * ### .deepOwnInclude(haystack, needle, [message])
             *
             * Asserts that 'haystack' includes 'needle'.
             * Can be used to assert the inclusion of a subset of properties in an
             * object while ignoring inherited properties and checking for deep equality.
             *
             *      assert.deepOwnInclude({a: {b: 2}}, {a: {b: 2}});
             *
             * @name deepOwnInclude
             * @param {Object} haystack
             * @param {Object} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.deepOwnInclude = function (exp, inc, msg) {
              new Assertion(
                exp,
                msg,
                assert.deepOwnInclude,
                true
              ).deep.own.include(inc)
            }

            /**
             * ### .notDeepOwnInclude(haystack, needle, [message])
             *
             * Asserts that 'haystack' includes 'needle'.
             * Can be used to assert the absence of a subset of properties in an
             * object while ignoring inherited properties and checking for deep equality.
             *
             *      assert.notDeepOwnInclude({a: {b: 2}}, {a: {c: 3}});
             *
             * @name notDeepOwnInclude
             * @param {Object} haystack
             * @param {Object} needle
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notDeepOwnInclude = function (exp, inc, msg) {
              new Assertion(
                exp,
                msg,
                assert.notDeepOwnInclude,
                true
              ).not.deep.own.include(inc)
            }

            /**
             * ### .match(value, regexp, [message])
             *
             * Asserts that `value` matches the regular expression `regexp`.
             *
             *     assert.match('foobar', /^foo/, 'regexp matches');
             *
             * @name match
             * @param {Mixed} value
             * @param {RegExp} regexp
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.match = function (exp, re, msg) {
              new Assertion(exp, msg, assert.match, true).to.match(re)
            }

            /**
             * ### .notMatch(value, regexp, [message])
             *
             * Asserts that `value` does not match the regular expression `regexp`.
             *
             *     assert.notMatch('foobar', /^foo/, 'regexp does not match');
             *
             * @name notMatch
             * @param {Mixed} value
             * @param {RegExp} regexp
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notMatch = function (exp, re, msg) {
              new Assertion(exp, msg, assert.notMatch, true).to.not.match(re)
            }

            /**
             * ### .property(object, property, [message])
             *
             * Asserts that `object` has a direct or inherited property named by
             * `property`.
             *
             *     assert.property({ tea: { green: 'matcha' }}, 'tea');
             *     assert.property({ tea: { green: 'matcha' }}, 'toString');
             *
             * @name property
             * @param {Object} object
             * @param {String} property
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.property = function (obj, prop, msg) {
              new Assertion(obj, msg, assert.property, true).to.have.property(
                prop
              )
            }

            /**
             * ### .notProperty(object, property, [message])
             *
             * Asserts that `object` does _not_ have a direct or inherited property named
             * by `property`.
             *
             *     assert.notProperty({ tea: { green: 'matcha' }}, 'coffee');
             *
             * @name notProperty
             * @param {Object} object
             * @param {String} property
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notProperty = function (obj, prop, msg) {
              new Assertion(
                obj,
                msg,
                assert.notProperty,
                true
              ).to.not.have.property(prop)
            }

            /**
             * ### .propertyVal(object, property, value, [message])
             *
             * Asserts that `object` has a direct or inherited property named by
             * `property` with a value given by `value`. Uses a strict equality check
             * (===).
             *
             *     assert.propertyVal({ tea: 'is good' }, 'tea', 'is good');
             *
             * @name propertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.propertyVal = function (obj, prop, val, msg) {
              new Assertion(
                obj,
                msg,
                assert.propertyVal,
                true
              ).to.have.property(prop, val)
            }

            /**
             * ### .notPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` does _not_ have a direct or inherited property named
             * by `property` with value given by `value`. Uses a strict equality check
             * (===).
             *
             *     assert.notPropertyVal({ tea: 'is good' }, 'tea', 'is bad');
             *     assert.notPropertyVal({ tea: 'is good' }, 'coffee', 'is good');
             *
             * @name notPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notPropertyVal = function (obj, prop, val, msg) {
              new Assertion(
                obj,
                msg,
                assert.notPropertyVal,
                true
              ).to.not.have.property(prop, val)
            }

            /**
             * ### .deepPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` has a direct or inherited property named by
             * `property` with a value given by `value`. Uses a deep equality check.
             *
             *     assert.deepPropertyVal({ tea: { green: 'matcha' } }, 'tea', { green: 'matcha' });
             *
             * @name deepPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.deepPropertyVal = function (obj, prop, val, msg) {
              new Assertion(
                obj,
                msg,
                assert.deepPropertyVal,
                true
              ).to.have.deep.property(prop, val)
            }

            /**
             * ### .notDeepPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` does _not_ have a direct or inherited property named
             * by `property` with value given by `value`. Uses a deep equality check.
             *
             *     assert.notDeepPropertyVal({ tea: { green: 'matcha' } }, 'tea', { black: 'matcha' });
             *     assert.notDeepPropertyVal({ tea: { green: 'matcha' } }, 'tea', { green: 'oolong' });
             *     assert.notDeepPropertyVal({ tea: { green: 'matcha' } }, 'coffee', { green: 'matcha' });
             *
             * @name notDeepPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notDeepPropertyVal = function (obj, prop, val, msg) {
              new Assertion(
                obj,
                msg,
                assert.notDeepPropertyVal,
                true
              ).to.not.have.deep.property(prop, val)
            }

            /**
             * ### .ownProperty(object, property, [message])
             *
             * Asserts that `object` has a direct property named by `property`. Inherited
             * properties aren't checked.
             *
             *     assert.ownProperty({ tea: { green: 'matcha' }}, 'tea');
             *
             * @name ownProperty
             * @param {Object} object
             * @param {String} property
             * @param {String} message
             * @api public
             */

            assert.ownProperty = function (obj, prop, msg) {
              new Assertion(
                obj,
                msg,
                assert.ownProperty,
                true
              ).to.have.own.property(prop)
            }

            /**
             * ### .notOwnProperty(object, property, [message])
             *
             * Asserts that `object` does _not_ have a direct property named by
             * `property`. Inherited properties aren't checked.
             *
             *     assert.notOwnProperty({ tea: { green: 'matcha' }}, 'coffee');
             *     assert.notOwnProperty({}, 'toString');
             *
             * @name notOwnProperty
             * @param {Object} object
             * @param {String} property
             * @param {String} message
             * @api public
             */

            assert.notOwnProperty = function (obj, prop, msg) {
              new Assertion(
                obj,
                msg,
                assert.notOwnProperty,
                true
              ).to.not.have.own.property(prop)
            }

            /**
             * ### .ownPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` has a direct property named by `property` and a value
             * equal to the provided `value`. Uses a strict equality check (===).
             * Inherited properties aren't checked.
             *
             *     assert.ownPropertyVal({ coffee: 'is good'}, 'coffee', 'is good');
             *
             * @name ownPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @api public
             */

            assert.ownPropertyVal = function (obj, prop, value, msg) {
              new Assertion(
                obj,
                msg,
                assert.ownPropertyVal,
                true
              ).to.have.own.property(prop, value)
            }

            /**
             * ### .notOwnPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` does _not_ have a direct property named by `property`
             * with a value equal to the provided `value`. Uses a strict equality check
             * (===). Inherited properties aren't checked.
             *
             *     assert.notOwnPropertyVal({ tea: 'is better'}, 'tea', 'is worse');
             *     assert.notOwnPropertyVal({}, 'toString', Object.prototype.toString);
             *
             * @name notOwnPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @api public
             */

            assert.notOwnPropertyVal = function (obj, prop, value, msg) {
              new Assertion(
                obj,
                msg,
                assert.notOwnPropertyVal,
                true
              ).to.not.have.own.property(prop, value)
            }

            /**
             * ### .deepOwnPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` has a direct property named by `property` and a value
             * equal to the provided `value`. Uses a deep equality check. Inherited
             * properties aren't checked.
             *
             *     assert.deepOwnPropertyVal({ tea: { green: 'matcha' } }, 'tea', { green: 'matcha' });
             *
             * @name deepOwnPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @api public
             */

            assert.deepOwnPropertyVal = function (obj, prop, value, msg) {
              new Assertion(
                obj,
                msg,
                assert.deepOwnPropertyVal,
                true
              ).to.have.deep.own.property(prop, value)
            }

            /**
             * ### .notDeepOwnPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` does _not_ have a direct property named by `property`
             * with a value equal to the provided `value`. Uses a deep equality check.
             * Inherited properties aren't checked.
             *
             *     assert.notDeepOwnPropertyVal({ tea: { green: 'matcha' } }, 'tea', { black: 'matcha' });
             *     assert.notDeepOwnPropertyVal({ tea: { green: 'matcha' } }, 'tea', { green: 'oolong' });
             *     assert.notDeepOwnPropertyVal({ tea: { green: 'matcha' } }, 'coffee', { green: 'matcha' });
             *     assert.notDeepOwnPropertyVal({}, 'toString', Object.prototype.toString);
             *
             * @name notDeepOwnPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @api public
             */

            assert.notDeepOwnPropertyVal = function (obj, prop, value, msg) {
              new Assertion(
                obj,
                msg,
                assert.notDeepOwnPropertyVal,
                true
              ).to.not.have.deep.own.property(prop, value)
            }

            /**
             * ### .nestedProperty(object, property, [message])
             *
             * Asserts that `object` has a direct or inherited property named by
             * `property`, which can be a string using dot- and bracket-notation for
             * nested reference.
             *
             *     assert.nestedProperty({ tea: { green: 'matcha' }}, 'tea.green');
             *
             * @name nestedProperty
             * @param {Object} object
             * @param {String} property
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.nestedProperty = function (obj, prop, msg) {
              new Assertion(
                obj,
                msg,
                assert.nestedProperty,
                true
              ).to.have.nested.property(prop)
            }

            /**
             * ### .notNestedProperty(object, property, [message])
             *
             * Asserts that `object` does _not_ have a property named by `property`, which
             * can be a string using dot- and bracket-notation for nested reference. The
             * property cannot exist on the object nor anywhere in its prototype chain.
             *
             *     assert.notNestedProperty({ tea: { green: 'matcha' }}, 'tea.oolong');
             *
             * @name notNestedProperty
             * @param {Object} object
             * @param {String} property
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notNestedProperty = function (obj, prop, msg) {
              new Assertion(
                obj,
                msg,
                assert.notNestedProperty,
                true
              ).to.not.have.nested.property(prop)
            }

            /**
             * ### .nestedPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` has a property named by `property` with value given
             * by `value`. `property` can use dot- and bracket-notation for nested
             * reference. Uses a strict equality check (===).
             *
             *     assert.nestedPropertyVal({ tea: { green: 'matcha' }}, 'tea.green', 'matcha');
             *
             * @name nestedPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.nestedPropertyVal = function (obj, prop, val, msg) {
              new Assertion(
                obj,
                msg,
                assert.nestedPropertyVal,
                true
              ).to.have.nested.property(prop, val)
            }

            /**
             * ### .notNestedPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` does _not_ have a property named by `property` with
             * value given by `value`. `property` can use dot- and bracket-notation for
             * nested reference. Uses a strict equality check (===).
             *
             *     assert.notNestedPropertyVal({ tea: { green: 'matcha' }}, 'tea.green', 'konacha');
             *     assert.notNestedPropertyVal({ tea: { green: 'matcha' }}, 'coffee.green', 'matcha');
             *
             * @name notNestedPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notNestedPropertyVal = function (obj, prop, val, msg) {
              new Assertion(
                obj,
                msg,
                assert.notNestedPropertyVal,
                true
              ).to.not.have.nested.property(prop, val)
            }

            /**
             * ### .deepNestedPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` has a property named by `property` with a value given
             * by `value`. `property` can use dot- and bracket-notation for nested
             * reference. Uses a deep equality check.
             *
             *     assert.deepNestedPropertyVal({ tea: { green: { matcha: 'yum' } } }, 'tea.green', { matcha: 'yum' });
             *
             * @name deepNestedPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.deepNestedPropertyVal = function (obj, prop, val, msg) {
              new Assertion(
                obj,
                msg,
                assert.deepNestedPropertyVal,
                true
              ).to.have.deep.nested.property(prop, val)
            }

            /**
             * ### .notDeepNestedPropertyVal(object, property, value, [message])
             *
             * Asserts that `object` does _not_ have a property named by `property` with
             * value given by `value`. `property` can use dot- and bracket-notation for
             * nested reference. Uses a deep equality check.
             *
             *     assert.notDeepNestedPropertyVal({ tea: { green: { matcha: 'yum' } } }, 'tea.green', { oolong: 'yum' });
             *     assert.notDeepNestedPropertyVal({ tea: { green: { matcha: 'yum' } } }, 'tea.green', { matcha: 'yuck' });
             *     assert.notDeepNestedPropertyVal({ tea: { green: { matcha: 'yum' } } }, 'tea.black', { matcha: 'yum' });
             *
             * @name notDeepNestedPropertyVal
             * @param {Object} object
             * @param {String} property
             * @param {Mixed} value
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notDeepNestedPropertyVal = function (obj, prop, val, msg) {
              new Assertion(
                obj,
                msg,
                assert.notDeepNestedPropertyVal,
                true
              ).to.not.have.deep.nested.property(prop, val)
            }

            /**
             * ### .lengthOf(object, length, [message])
             *
             * Asserts that `object` has a `length` or `size` with the expected value.
             *
             *     assert.lengthOf([1,2,3], 3, 'array has length of 3');
             *     assert.lengthOf('foobar', 6, 'string has length of 6');
             *     assert.lengthOf(new Set([1,2,3]), 3, 'set has size of 3');
             *     assert.lengthOf(new Map([['a',1],['b',2],['c',3]]), 3, 'map has size of 3');
             *
             * @name lengthOf
             * @param {Mixed} object
             * @param {Number} length
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.lengthOf = function (exp, len, msg) {
              new Assertion(exp, msg, assert.lengthOf, true).to.have.lengthOf(
                len
              )
            }

            /**
             * ### .hasAnyKeys(object, [keys], [message])
             *
             * Asserts that `object` has at least one of the `keys` provided.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.hasAnyKeys({foo: 1, bar: 2, baz: 3}, ['foo', 'iDontExist', 'baz']);
             *     assert.hasAnyKeys({foo: 1, bar: 2, baz: 3}, {foo: 30, iDontExist: 99, baz: 1337});
             *     assert.hasAnyKeys(new Map([[{foo: 1}, 'bar'], ['key', 'value']]), [{foo: 1}, 'key']);
             *     assert.hasAnyKeys(new Set([{foo: 'bar'}, 'anotherKey']), [{foo: 'bar'}, 'anotherKey']);
             *
             * @name hasAnyKeys
             * @param {Mixed} object
             * @param {Array|Object} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.hasAnyKeys = function (obj, keys, msg) {
              new Assertion(obj, msg, assert.hasAnyKeys, true).to.have.any.keys(
                keys
              )
            }

            /**
             * ### .hasAllKeys(object, [keys], [message])
             *
             * Asserts that `object` has all and only all of the `keys` provided.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.hasAllKeys({foo: 1, bar: 2, baz: 3}, ['foo', 'bar', 'baz']);
             *     assert.hasAllKeys({foo: 1, bar: 2, baz: 3}, {foo: 30, bar: 99, baz: 1337]);
             *     assert.hasAllKeys(new Map([[{foo: 1}, 'bar'], ['key', 'value']]), [{foo: 1}, 'key']);
             *     assert.hasAllKeys(new Set([{foo: 'bar'}, 'anotherKey'], [{foo: 'bar'}, 'anotherKey']);
             *
             * @name hasAllKeys
             * @param {Mixed} object
             * @param {String[]} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.hasAllKeys = function (obj, keys, msg) {
              new Assertion(obj, msg, assert.hasAllKeys, true).to.have.all.keys(
                keys
              )
            }

            /**
             * ### .containsAllKeys(object, [keys], [message])
             *
             * Asserts that `object` has all of the `keys` provided but may have more keys not listed.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.containsAllKeys({foo: 1, bar: 2, baz: 3}, ['foo', 'baz']);
             *     assert.containsAllKeys({foo: 1, bar: 2, baz: 3}, ['foo', 'bar', 'baz']);
             *     assert.containsAllKeys({foo: 1, bar: 2, baz: 3}, {foo: 30, baz: 1337});
             *     assert.containsAllKeys({foo: 1, bar: 2, baz: 3}, {foo: 30, bar: 99, baz: 1337});
             *     assert.containsAllKeys(new Map([[{foo: 1}, 'bar'], ['key', 'value']]), [{foo: 1}]);
             *     assert.containsAllKeys(new Map([[{foo: 1}, 'bar'], ['key', 'value']]), [{foo: 1}, 'key']);
             *     assert.containsAllKeys(new Set([{foo: 'bar'}, 'anotherKey'], [{foo: 'bar'}]);
             *     assert.containsAllKeys(new Set([{foo: 'bar'}, 'anotherKey'], [{foo: 'bar'}, 'anotherKey']);
             *
             * @name containsAllKeys
             * @param {Mixed} object
             * @param {String[]} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.containsAllKeys = function (obj, keys, msg) {
              new Assertion(
                obj,
                msg,
                assert.containsAllKeys,
                true
              ).to.contain.all.keys(keys)
            }

            /**
             * ### .doesNotHaveAnyKeys(object, [keys], [message])
             *
             * Asserts that `object` has none of the `keys` provided.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.doesNotHaveAnyKeys({foo: 1, bar: 2, baz: 3}, ['one', 'two', 'example']);
             *     assert.doesNotHaveAnyKeys({foo: 1, bar: 2, baz: 3}, {one: 1, two: 2, example: 'foo'});
             *     assert.doesNotHaveAnyKeys(new Map([[{foo: 1}, 'bar'], ['key', 'value']]), [{one: 'two'}, 'example']);
             *     assert.doesNotHaveAnyKeys(new Set([{foo: 'bar'}, 'anotherKey'], [{one: 'two'}, 'example']);
             *
             * @name doesNotHaveAnyKeys
             * @param {Mixed} object
             * @param {String[]} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.doesNotHaveAnyKeys = function (obj, keys, msg) {
              new Assertion(
                obj,
                msg,
                assert.doesNotHaveAnyKeys,
                true
              ).to.not.have.any.keys(keys)
            }

            /**
             * ### .doesNotHaveAllKeys(object, [keys], [message])
             *
             * Asserts that `object` does not have at least one of the `keys` provided.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.doesNotHaveAllKeys({foo: 1, bar: 2, baz: 3}, ['one', 'two', 'example']);
             *     assert.doesNotHaveAllKeys({foo: 1, bar: 2, baz: 3}, {one: 1, two: 2, example: 'foo'});
             *     assert.doesNotHaveAllKeys(new Map([[{foo: 1}, 'bar'], ['key', 'value']]), [{one: 'two'}, 'example']);
             *     assert.doesNotHaveAllKeys(new Set([{foo: 'bar'}, 'anotherKey'], [{one: 'two'}, 'example']);
             *
             * @name doesNotHaveAllKeys
             * @param {Mixed} object
             * @param {String[]} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.doesNotHaveAllKeys = function (obj, keys, msg) {
              new Assertion(
                obj,
                msg,
                assert.doesNotHaveAllKeys,
                true
              ).to.not.have.all.keys(keys)
            }

            /**
             * ### .hasAnyDeepKeys(object, [keys], [message])
             *
             * Asserts that `object` has at least one of the `keys` provided.
             * Since Sets and Maps can have objects as keys you can use this assertion to perform
             * a deep comparison.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.hasAnyDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [1, 2]]), {one: 'one'});
             *     assert.hasAnyDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [1, 2]]), [{one: 'one'}, {two: 'two'}]);
             *     assert.hasAnyDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [{two: 'two'}, 'valueTwo']]), [{one: 'one'}, {two: 'two'}]);
             *     assert.hasAnyDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), {one: 'one'});
             *     assert.hasAnyDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), [{one: 'one'}, {three: 'three'}]);
             *     assert.hasAnyDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), [{one: 'one'}, {two: 'two'}]);
             *
             * @name hasAnyDeepKeys
             * @param {Mixed} object
             * @param {Array|Object} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.hasAnyDeepKeys = function (obj, keys, msg) {
              new Assertion(
                obj,
                msg,
                assert.hasAnyDeepKeys,
                true
              ).to.have.any.deep.keys(keys)
            }

            /**
             * ### .hasAllDeepKeys(object, [keys], [message])
             *
             * Asserts that `object` has all and only all of the `keys` provided.
             * Since Sets and Maps can have objects as keys you can use this assertion to perform
             * a deep comparison.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.hasAllDeepKeys(new Map([[{one: 'one'}, 'valueOne']]), {one: 'one'});
             *     assert.hasAllDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [{two: 'two'}, 'valueTwo']]), [{one: 'one'}, {two: 'two'}]);
             *     assert.hasAllDeepKeys(new Set([{one: 'one'}]), {one: 'one'});
             *     assert.hasAllDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), [{one: 'one'}, {two: 'two'}]);
             *
             * @name hasAllDeepKeys
             * @param {Mixed} object
             * @param {Array|Object} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.hasAllDeepKeys = function (obj, keys, msg) {
              new Assertion(
                obj,
                msg,
                assert.hasAllDeepKeys,
                true
              ).to.have.all.deep.keys(keys)
            }

            /**
             * ### .containsAllDeepKeys(object, [keys], [message])
             *
             * Asserts that `object` contains all of the `keys` provided.
             * Since Sets and Maps can have objects as keys you can use this assertion to perform
             * a deep comparison.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.containsAllDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [1, 2]]), {one: 'one'});
             *     assert.containsAllDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [{two: 'two'}, 'valueTwo']]), [{one: 'one'}, {two: 'two'}]);
             *     assert.containsAllDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), {one: 'one'});
             *     assert.containsAllDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), [{one: 'one'}, {two: 'two'}]);
             *
             * @name containsAllDeepKeys
             * @param {Mixed} object
             * @param {Array|Object} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.containsAllDeepKeys = function (obj, keys, msg) {
              new Assertion(
                obj,
                msg,
                assert.containsAllDeepKeys,
                true
              ).to.contain.all.deep.keys(keys)
            }

            /**
             * ### .doesNotHaveAnyDeepKeys(object, [keys], [message])
             *
             * Asserts that `object` has none of the `keys` provided.
             * Since Sets and Maps can have objects as keys you can use this assertion to perform
             * a deep comparison.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.doesNotHaveAnyDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [1, 2]]), {thisDoesNot: 'exist'});
             *     assert.doesNotHaveAnyDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [{two: 'two'}, 'valueTwo']]), [{twenty: 'twenty'}, {fifty: 'fifty'}]);
             *     assert.doesNotHaveAnyDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), {twenty: 'twenty'});
             *     assert.doesNotHaveAnyDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), [{twenty: 'twenty'}, {fifty: 'fifty'}]);
             *
             * @name doesNotHaveAnyDeepKeys
             * @param {Mixed} object
             * @param {Array|Object} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.doesNotHaveAnyDeepKeys = function (obj, keys, msg) {
              new Assertion(
                obj,
                msg,
                assert.doesNotHaveAnyDeepKeys,
                true
              ).to.not.have.any.deep.keys(keys)
            }

            /**
             * ### .doesNotHaveAllDeepKeys(object, [keys], [message])
             *
             * Asserts that `object` does not have at least one of the `keys` provided.
             * Since Sets and Maps can have objects as keys you can use this assertion to perform
             * a deep comparison.
             * You can also provide a single object instead of a `keys` array and its keys
             * will be used as the expected set of keys.
             *
             *     assert.doesNotHaveAllDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [1, 2]]), {thisDoesNot: 'exist'});
             *     assert.doesNotHaveAllDeepKeys(new Map([[{one: 'one'}, 'valueOne'], [{two: 'two'}, 'valueTwo']]), [{twenty: 'twenty'}, {one: 'one'}]);
             *     assert.doesNotHaveAllDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), {twenty: 'twenty'});
             *     assert.doesNotHaveAllDeepKeys(new Set([{one: 'one'}, {two: 'two'}]), [{one: 'one'}, {fifty: 'fifty'}]);
             *
             * @name doesNotHaveAllDeepKeys
             * @param {Mixed} object
             * @param {Array|Object} keys
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.doesNotHaveAllDeepKeys = function (obj, keys, msg) {
              new Assertion(
                obj,
                msg,
                assert.doesNotHaveAllDeepKeys,
                true
              ).to.not.have.all.deep.keys(keys)
            }

            /**
             * ### .throws(fn, [errorLike/string/regexp], [string/regexp], [message])
             *
             * If `errorLike` is an `Error` constructor, asserts that `fn` will throw an error that is an
             * instance of `errorLike`.
             * If `errorLike` is an `Error` instance, asserts that the error thrown is the same
             * instance as `errorLike`.
             * If `errMsgMatcher` is provided, it also asserts that the error thrown will have a
             * message matching `errMsgMatcher`.
             *
             *     assert.throws(fn, 'Error thrown must have this msg');
             *     assert.throws(fn, /Error thrown must have a msg that matches this/);
             *     assert.throws(fn, ReferenceError);
             *     assert.throws(fn, errorInstance);
             *     assert.throws(fn, ReferenceError, 'Error thrown must be a ReferenceError and have this msg');
             *     assert.throws(fn, errorInstance, 'Error thrown must be the same errorInstance and have this msg');
             *     assert.throws(fn, ReferenceError, /Error thrown must be a ReferenceError and match this/);
             *     assert.throws(fn, errorInstance, /Error thrown must be the same errorInstance and match this/);
             *
             * @name throws
             * @alias throw
             * @alias Throw
             * @param {Function} fn
             * @param {ErrorConstructor|Error} errorLike
             * @param {RegExp|String} errMsgMatcher
             * @param {String} message
             * @see https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Error#Error_types
             * @namespace Assert
             * @api public
             */

            assert.throws = function (fn, errorLike, errMsgMatcher, msg) {
              if (
                'string' === typeof errorLike ||
                errorLike instanceof RegExp
              ) {
                errMsgMatcher = errorLike
                errorLike = null
              }

              var assertErr = new Assertion(
                fn,
                msg,
                assert.throws,
                true
              ).to.throw(errorLike, errMsgMatcher)
              return flag(assertErr, 'object')
            }

            /**
             * ### .doesNotThrow(fn, [errorLike/string/regexp], [string/regexp], [message])
             *
             * If `errorLike` is an `Error` constructor, asserts that `fn` will _not_ throw an error that is an
             * instance of `errorLike`.
             * If `errorLike` is an `Error` instance, asserts that the error thrown is _not_ the same
             * instance as `errorLike`.
             * If `errMsgMatcher` is provided, it also asserts that the error thrown will _not_ have a
             * message matching `errMsgMatcher`.
             *
             *     assert.doesNotThrow(fn, 'Any Error thrown must not have this message');
             *     assert.doesNotThrow(fn, /Any Error thrown must not match this/);
             *     assert.doesNotThrow(fn, Error);
             *     assert.doesNotThrow(fn, errorInstance);
             *     assert.doesNotThrow(fn, Error, 'Error must not have this message');
             *     assert.doesNotThrow(fn, errorInstance, 'Error must not have this message');
             *     assert.doesNotThrow(fn, Error, /Error must not match this/);
             *     assert.doesNotThrow(fn, errorInstance, /Error must not match this/);
             *
             * @name doesNotThrow
             * @param {Function} fn
             * @param {ErrorConstructor} errorLike
             * @param {RegExp|String} errMsgMatcher
             * @param {String} message
             * @see https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Error#Error_types
             * @namespace Assert
             * @api public
             */

            assert.doesNotThrow = function (fn, errorLike, errMsgMatcher, msg) {
              if (
                'string' === typeof errorLike ||
                errorLike instanceof RegExp
              ) {
                errMsgMatcher = errorLike
                errorLike = null
              }

              new Assertion(fn, msg, assert.doesNotThrow, true).to.not.throw(
                errorLike,
                errMsgMatcher
              )
            }

            /**
             * ### .operator(val1, operator, val2, [message])
             *
             * Compares two values using `operator`.
             *
             *     assert.operator(1, '<', 2, 'everything is ok');
             *     assert.operator(1, '>', 2, 'this will fail');
             *
             * @name operator
             * @param {Mixed} val1
             * @param {String} operator
             * @param {Mixed} val2
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.operator = function (val, operator, val2, msg) {
              var ok
              switch (operator) {
                case '==':
                  ok = val == val2
                  break
                case '===':
                  ok = val === val2
                  break
                case '>':
                  ok = val > val2
                  break
                case '>=':
                  ok = val >= val2
                  break
                case '<':
                  ok = val < val2
                  break
                case '<=':
                  ok = val <= val2
                  break
                case '!=':
                  ok = val != val2
                  break
                case '!==':
                  ok = val !== val2
                  break
                default:
                  msg = msg ? msg + ': ' : msg
                  throw new chai.AssertionError(
                    msg + 'Invalid operator "' + operator + '"',
                    undefined,
                    assert.operator
                  )
              }
              var test = new Assertion(ok, msg, assert.operator, true)
              test.assert(
                true === flag(test, 'object'),
                'expected ' +
                  util.inspect(val) +
                  ' to be ' +
                  operator +
                  ' ' +
                  util.inspect(val2),
                'expected ' +
                  util.inspect(val) +
                  ' to not be ' +
                  operator +
                  ' ' +
                  util.inspect(val2)
              )
            }

            /**
             * ### .closeTo(actual, expected, delta, [message])
             *
             * Asserts that the target is equal `expected`, to within a +/- `delta` range.
             *
             *     assert.closeTo(1.5, 1, 0.5, 'numbers are close');
             *
             * @name closeTo
             * @param {Number} actual
             * @param {Number} expected
             * @param {Number} delta
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.closeTo = function (act, exp, delta, msg) {
              new Assertion(act, msg, assert.closeTo, true).to.be.closeTo(
                exp,
                delta
              )
            }

            /**
             * ### .approximately(actual, expected, delta, [message])
             *
             * Asserts that the target is equal `expected`, to within a +/- `delta` range.
             *
             *     assert.approximately(1.5, 1, 0.5, 'numbers are close');
             *
             * @name approximately
             * @param {Number} actual
             * @param {Number} expected
             * @param {Number} delta
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.approximately = function (act, exp, delta, msg) {
              new Assertion(
                act,
                msg,
                assert.approximately,
                true
              ).to.be.approximately(exp, delta)
            }

            /**
             * ### .sameMembers(set1, set2, [message])
             *
             * Asserts that `set1` and `set2` have the same members in any order. Uses a
             * strict equality check (===).
             *
             *     assert.sameMembers([ 1, 2, 3 ], [ 2, 1, 3 ], 'same members');
             *
             * @name sameMembers
             * @param {Array} set1
             * @param {Array} set2
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.sameMembers = function (set1, set2, msg) {
              new Assertion(
                set1,
                msg,
                assert.sameMembers,
                true
              ).to.have.same.members(set2)
            }

            /**
             * ### .notSameMembers(set1, set2, [message])
             *
             * Asserts that `set1` and `set2` don't have the same members in any order.
             * Uses a strict equality check (===).
             *
             *     assert.notSameMembers([ 1, 2, 3 ], [ 5, 1, 3 ], 'not same members');
             *
             * @name notSameMembers
             * @param {Array} set1
             * @param {Array} set2
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notSameMembers = function (set1, set2, msg) {
              new Assertion(
                set1,
                msg,
                assert.notSameMembers,
                true
              ).to.not.have.same.members(set2)
            }

            /**
             * ### .sameDeepMembers(set1, set2, [message])
             *
             * Asserts that `set1` and `set2` have the same members in any order. Uses a
             * deep equality check.
             *
             *     assert.sameDeepMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [{ b: 2 }, { a: 1 }, { c: 3 }], 'same deep members');
             *
             * @name sameDeepMembers
             * @param {Array} set1
             * @param {Array} set2
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.sameDeepMembers = function (set1, set2, msg) {
              new Assertion(
                set1,
                msg,
                assert.sameDeepMembers,
                true
              ).to.have.same.deep.members(set2)
            }

            /**
             * ### .notSameDeepMembers(set1, set2, [message])
             *
             * Asserts that `set1` and `set2` don't have the same members in any order.
             * Uses a deep equality check.
             *
             *     assert.notSameDeepMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [{ b: 2 }, { a: 1 }, { f: 5 }], 'not same deep members');
             *
             * @name notSameDeepMembers
             * @param {Array} set1
             * @param {Array} set2
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notSameDeepMembers = function (set1, set2, msg) {
              new Assertion(
                set1,
                msg,
                assert.notSameDeepMembers,
                true
              ).to.not.have.same.deep.members(set2)
            }

            /**
             * ### .sameOrderedMembers(set1, set2, [message])
             *
             * Asserts that `set1` and `set2` have the same members in the same order.
             * Uses a strict equality check (===).
             *
             *     assert.sameOrderedMembers([ 1, 2, 3 ], [ 1, 2, 3 ], 'same ordered members');
             *
             * @name sameOrderedMembers
             * @param {Array} set1
             * @param {Array} set2
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.sameOrderedMembers = function (set1, set2, msg) {
              new Assertion(
                set1,
                msg,
                assert.sameOrderedMembers,
                true
              ).to.have.same.ordered.members(set2)
            }

            /**
             * ### .notSameOrderedMembers(set1, set2, [message])
             *
             * Asserts that `set1` and `set2` don't have the same members in the same
             * order. Uses a strict equality check (===).
             *
             *     assert.notSameOrderedMembers([ 1, 2, 3 ], [ 2, 1, 3 ], 'not same ordered members');
             *
             * @name notSameOrderedMembers
             * @param {Array} set1
             * @param {Array} set2
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notSameOrderedMembers = function (set1, set2, msg) {
              new Assertion(
                set1,
                msg,
                assert.notSameOrderedMembers,
                true
              ).to.not.have.same.ordered.members(set2)
            }

            /**
             * ### .sameDeepOrderedMembers(set1, set2, [message])
             *
             * Asserts that `set1` and `set2` have the same members in the same order.
             * Uses a deep equality check.
             *
             *     assert.sameDeepOrderedMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [ { a: 1 }, { b: 2 }, { c: 3 } ], 'same deep ordered members');
             *
             * @name sameDeepOrderedMembers
             * @param {Array} set1
             * @param {Array} set2
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.sameDeepOrderedMembers = function (set1, set2, msg) {
              new Assertion(
                set1,
                msg,
                assert.sameDeepOrderedMembers,
                true
              ).to.have.same.deep.ordered.members(set2)
            }

            /**
             * ### .notSameDeepOrderedMembers(set1, set2, [message])
             *
             * Asserts that `set1` and `set2` don't have the same members in the same
             * order. Uses a deep equality check.
             *
             *     assert.notSameDeepOrderedMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [ { a: 1 }, { b: 2 }, { z: 5 } ], 'not same deep ordered members');
             *     assert.notSameDeepOrderedMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [ { b: 2 }, { a: 1 }, { c: 3 } ], 'not same deep ordered members');
             *
             * @name notSameDeepOrderedMembers
             * @param {Array} set1
             * @param {Array} set2
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notSameDeepOrderedMembers = function (set1, set2, msg) {
              new Assertion(
                set1,
                msg,
                assert.notSameDeepOrderedMembers,
                true
              ).to.not.have.same.deep.ordered.members(set2)
            }

            /**
             * ### .includeMembers(superset, subset, [message])
             *
             * Asserts that `subset` is included in `superset` in any order. Uses a
             * strict equality check (===). Duplicates are ignored.
             *
             *     assert.includeMembers([ 1, 2, 3 ], [ 2, 1, 2 ], 'include members');
             *
             * @name includeMembers
             * @param {Array} superset
             * @param {Array} subset
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.includeMembers = function (superset, subset, msg) {
              new Assertion(
                superset,
                msg,
                assert.includeMembers,
                true
              ).to.include.members(subset)
            }

            /**
             * ### .notIncludeMembers(superset, subset, [message])
             *
             * Asserts that `subset` isn't included in `superset` in any order. Uses a
             * strict equality check (===). Duplicates are ignored.
             *
             *     assert.notIncludeMembers([ 1, 2, 3 ], [ 5, 1 ], 'not include members');
             *
             * @name notIncludeMembers
             * @param {Array} superset
             * @param {Array} subset
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notIncludeMembers = function (superset, subset, msg) {
              new Assertion(
                superset,
                msg,
                assert.notIncludeMembers,
                true
              ).to.not.include.members(subset)
            }

            /**
             * ### .includeDeepMembers(superset, subset, [message])
             *
             * Asserts that `subset` is included in `superset` in any order. Uses a deep
             * equality check. Duplicates are ignored.
             *
             *     assert.includeDeepMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [ { b: 2 }, { a: 1 }, { b: 2 } ], 'include deep members');
             *
             * @name includeDeepMembers
             * @param {Array} superset
             * @param {Array} subset
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.includeDeepMembers = function (superset, subset, msg) {
              new Assertion(
                superset,
                msg,
                assert.includeDeepMembers,
                true
              ).to.include.deep.members(subset)
            }

            /**
             * ### .notIncludeDeepMembers(superset, subset, [message])
             *
             * Asserts that `subset` isn't included in `superset` in any order. Uses a
             * deep equality check. Duplicates are ignored.
             *
             *     assert.notIncludeDeepMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [ { b: 2 }, { f: 5 } ], 'not include deep members');
             *
             * @name notIncludeDeepMembers
             * @param {Array} superset
             * @param {Array} subset
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notIncludeDeepMembers = function (superset, subset, msg) {
              new Assertion(
                superset,
                msg,
                assert.notIncludeDeepMembers,
                true
              ).to.not.include.deep.members(subset)
            }

            /**
             * ### .includeOrderedMembers(superset, subset, [message])
             *
             * Asserts that `subset` is included in `superset` in the same order
             * beginning with the first element in `superset`. Uses a strict equality
             * check (===).
             *
             *     assert.includeOrderedMembers([ 1, 2, 3 ], [ 1, 2 ], 'include ordered members');
             *
             * @name includeOrderedMembers
             * @param {Array} superset
             * @param {Array} subset
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.includeOrderedMembers = function (superset, subset, msg) {
              new Assertion(
                superset,
                msg,
                assert.includeOrderedMembers,
                true
              ).to.include.ordered.members(subset)
            }

            /**
             * ### .notIncludeOrderedMembers(superset, subset, [message])
             *
             * Asserts that `subset` isn't included in `superset` in the same order
             * beginning with the first element in `superset`. Uses a strict equality
             * check (===).
             *
             *     assert.notIncludeOrderedMembers([ 1, 2, 3 ], [ 2, 1 ], 'not include ordered members');
             *     assert.notIncludeOrderedMembers([ 1, 2, 3 ], [ 2, 3 ], 'not include ordered members');
             *
             * @name notIncludeOrderedMembers
             * @param {Array} superset
             * @param {Array} subset
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notIncludeOrderedMembers = function (superset, subset, msg) {
              new Assertion(
                superset,
                msg,
                assert.notIncludeOrderedMembers,
                true
              ).to.not.include.ordered.members(subset)
            }

            /**
             * ### .includeDeepOrderedMembers(superset, subset, [message])
             *
             * Asserts that `subset` is included in `superset` in the same order
             * beginning with the first element in `superset`. Uses a deep equality
             * check.
             *
             *     assert.includeDeepOrderedMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [ { a: 1 }, { b: 2 } ], 'include deep ordered members');
             *
             * @name includeDeepOrderedMembers
             * @param {Array} superset
             * @param {Array} subset
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.includeDeepOrderedMembers = function (
              superset,
              subset,
              msg
            ) {
              new Assertion(
                superset,
                msg,
                assert.includeDeepOrderedMembers,
                true
              ).to.include.deep.ordered.members(subset)
            }

            /**
             * ### .notIncludeDeepOrderedMembers(superset, subset, [message])
             *
             * Asserts that `subset` isn't included in `superset` in the same order
             * beginning with the first element in `superset`. Uses a deep equality
             * check.
             *
             *     assert.notIncludeDeepOrderedMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [ { a: 1 }, { f: 5 } ], 'not include deep ordered members');
             *     assert.notIncludeDeepOrderedMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [ { b: 2 }, { a: 1 } ], 'not include deep ordered members');
             *     assert.notIncludeDeepOrderedMembers([ { a: 1 }, { b: 2 }, { c: 3 } ], [ { b: 2 }, { c: 3 } ], 'not include deep ordered members');
             *
             * @name notIncludeDeepOrderedMembers
             * @param {Array} superset
             * @param {Array} subset
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.notIncludeDeepOrderedMembers = function (
              superset,
              subset,
              msg
            ) {
              new Assertion(
                superset,
                msg,
                assert.notIncludeDeepOrderedMembers,
                true
              ).to.not.include.deep.ordered.members(subset)
            }

            /**
             * ### .oneOf(inList, list, [message])
             *
             * Asserts that non-object, non-array value `inList` appears in the flat array `list`.
             *
             *     assert.oneOf(1, [ 2, 1 ], 'Not found in list');
             *
             * @name oneOf
             * @param {*} inList
             * @param {Array<*>} list
             * @param {String} message
             * @namespace Assert
             * @api public
             */

            assert.oneOf = function (inList, list, msg) {
              new Assertion(inList, msg, assert.oneOf, true).to.be.oneOf(list)
            }

            /**
             * ### .changes(function, object, property, [message])
             *
             * Asserts that a function changes the value of a property.
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val = 22 };
             *     assert.changes(fn, obj, 'val');
             *
             * @name changes
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.changes = function (fn, obj, prop, msg) {
              if (arguments.length === 3 && typeof obj === 'function') {
                msg = prop
                prop = null
              }

              new Assertion(fn, msg, assert.changes, true).to.change(obj, prop)
            }

            /**
             * ### .changesBy(function, object, property, delta, [message])
             *
             * Asserts that a function changes the value of a property by an amount (delta).
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val += 2 };
             *     assert.changesBy(fn, obj, 'val', 2);
             *
             * @name changesBy
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {Number} change amount (delta)
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.changesBy = function (fn, obj, prop, delta, msg) {
              if (arguments.length === 4 && typeof obj === 'function') {
                var tmpMsg = delta
                delta = prop
                msg = tmpMsg
              } else if (arguments.length === 3) {
                delta = prop
                prop = null
              }

              new Assertion(fn, msg, assert.changesBy, true).to
                .change(obj, prop)
                .by(delta)
            }

            /**
             * ### .doesNotChange(function, object, property, [message])
             *
             * Asserts that a function does not change the value of a property.
             *
             *     var obj = { val: 10 };
             *     var fn = function() { console.log('foo'); };
             *     assert.doesNotChange(fn, obj, 'val');
             *
             * @name doesNotChange
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.doesNotChange = function (fn, obj, prop, msg) {
              if (arguments.length === 3 && typeof obj === 'function') {
                msg = prop
                prop = null
              }

              return new Assertion(
                fn,
                msg,
                assert.doesNotChange,
                true
              ).to.not.change(obj, prop)
            }

            /**
             * ### .changesButNotBy(function, object, property, delta, [message])
             *
             * Asserts that a function does not change the value of a property or of a function's return value by an amount (delta)
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val += 10 };
             *     assert.changesButNotBy(fn, obj, 'val', 5);
             *
             * @name changesButNotBy
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {Number} change amount (delta)
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.changesButNotBy = function (fn, obj, prop, delta, msg) {
              if (arguments.length === 4 && typeof obj === 'function') {
                var tmpMsg = delta
                delta = prop
                msg = tmpMsg
              } else if (arguments.length === 3) {
                delta = prop
                prop = null
              }

              new Assertion(fn, msg, assert.changesButNotBy, true).to
                .change(obj, prop)
                .but.not.by(delta)
            }

            /**
             * ### .increases(function, object, property, [message])
             *
             * Asserts that a function increases a numeric object property.
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val = 13 };
             *     assert.increases(fn, obj, 'val');
             *
             * @name increases
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.increases = function (fn, obj, prop, msg) {
              if (arguments.length === 3 && typeof obj === 'function') {
                msg = prop
                prop = null
              }

              return new Assertion(fn, msg, assert.increases, true).to.increase(
                obj,
                prop
              )
            }

            /**
             * ### .increasesBy(function, object, property, delta, [message])
             *
             * Asserts that a function increases a numeric object property or a function's return value by an amount (delta).
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val += 10 };
             *     assert.increasesBy(fn, obj, 'val', 10);
             *
             * @name increasesBy
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {Number} change amount (delta)
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.increasesBy = function (fn, obj, prop, delta, msg) {
              if (arguments.length === 4 && typeof obj === 'function') {
                var tmpMsg = delta
                delta = prop
                msg = tmpMsg
              } else if (arguments.length === 3) {
                delta = prop
                prop = null
              }

              new Assertion(fn, msg, assert.increasesBy, true).to
                .increase(obj, prop)
                .by(delta)
            }

            /**
             * ### .doesNotIncrease(function, object, property, [message])
             *
             * Asserts that a function does not increase a numeric object property.
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val = 8 };
             *     assert.doesNotIncrease(fn, obj, 'val');
             *
             * @name doesNotIncrease
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.doesNotIncrease = function (fn, obj, prop, msg) {
              if (arguments.length === 3 && typeof obj === 'function') {
                msg = prop
                prop = null
              }

              return new Assertion(
                fn,
                msg,
                assert.doesNotIncrease,
                true
              ).to.not.increase(obj, prop)
            }

            /**
             * ### .increasesButNotBy(function, object, property, delta, [message])
             *
             * Asserts that a function does not increase a numeric object property or function's return value by an amount (delta).
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val = 15 };
             *     assert.increasesButNotBy(fn, obj, 'val', 10);
             *
             * @name increasesButNotBy
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {Number} change amount (delta)
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.increasesButNotBy = function (fn, obj, prop, delta, msg) {
              if (arguments.length === 4 && typeof obj === 'function') {
                var tmpMsg = delta
                delta = prop
                msg = tmpMsg
              } else if (arguments.length === 3) {
                delta = prop
                prop = null
              }

              new Assertion(fn, msg, assert.increasesButNotBy, true).to
                .increase(obj, prop)
                .but.not.by(delta)
            }

            /**
             * ### .decreases(function, object, property, [message])
             *
             * Asserts that a function decreases a numeric object property.
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val = 5 };
             *     assert.decreases(fn, obj, 'val');
             *
             * @name decreases
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.decreases = function (fn, obj, prop, msg) {
              if (arguments.length === 3 && typeof obj === 'function') {
                msg = prop
                prop = null
              }

              return new Assertion(fn, msg, assert.decreases, true).to.decrease(
                obj,
                prop
              )
            }

            /**
             * ### .decreasesBy(function, object, property, delta, [message])
             *
             * Asserts that a function decreases a numeric object property or a function's return value by an amount (delta)
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val -= 5 };
             *     assert.decreasesBy(fn, obj, 'val', 5);
             *
             * @name decreasesBy
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {Number} change amount (delta)
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.decreasesBy = function (fn, obj, prop, delta, msg) {
              if (arguments.length === 4 && typeof obj === 'function') {
                var tmpMsg = delta
                delta = prop
                msg = tmpMsg
              } else if (arguments.length === 3) {
                delta = prop
                prop = null
              }

              new Assertion(fn, msg, assert.decreasesBy, true).to
                .decrease(obj, prop)
                .by(delta)
            }

            /**
             * ### .doesNotDecrease(function, object, property, [message])
             *
             * Asserts that a function does not decreases a numeric object property.
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val = 15 };
             *     assert.doesNotDecrease(fn, obj, 'val');
             *
             * @name doesNotDecrease
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.doesNotDecrease = function (fn, obj, prop, msg) {
              if (arguments.length === 3 && typeof obj === 'function') {
                msg = prop
                prop = null
              }

              return new Assertion(
                fn,
                msg,
                assert.doesNotDecrease,
                true
              ).to.not.decrease(obj, prop)
            }

            /**
             * ### .doesNotDecreaseBy(function, object, property, delta, [message])
             *
             * Asserts that a function does not decreases a numeric object property or a function's return value by an amount (delta)
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val = 5 };
             *     assert.doesNotDecreaseBy(fn, obj, 'val', 1);
             *
             * @name doesNotDecreaseBy
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {Number} change amount (delta)
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.doesNotDecreaseBy = function (fn, obj, prop, delta, msg) {
              if (arguments.length === 4 && typeof obj === 'function') {
                var tmpMsg = delta
                delta = prop
                msg = tmpMsg
              } else if (arguments.length === 3) {
                delta = prop
                prop = null
              }

              return new Assertion(
                fn,
                msg,
                assert.doesNotDecreaseBy,
                true
              ).to.not
                .decrease(obj, prop)
                .by(delta)
            }

            /**
             * ### .decreasesButNotBy(function, object, property, delta, [message])
             *
             * Asserts that a function does not decreases a numeric object property or a function's return value by an amount (delta)
             *
             *     var obj = { val: 10 };
             *     var fn = function() { obj.val = 5 };
             *     assert.decreasesButNotBy(fn, obj, 'val', 1);
             *
             * @name decreasesButNotBy
             * @param {Function} modifier function
             * @param {Object} object or getter function
             * @param {String} property name _optional_
             * @param {Number} change amount (delta)
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.decreasesButNotBy = function (fn, obj, prop, delta, msg) {
              if (arguments.length === 4 && typeof obj === 'function') {
                var tmpMsg = delta
                delta = prop
                msg = tmpMsg
              } else if (arguments.length === 3) {
                delta = prop
                prop = null
              }

              new Assertion(fn, msg, assert.decreasesButNotBy, true).to
                .decrease(obj, prop)
                .but.not.by(delta)
            }

            /*!
             * ### .ifError(object)
             *
             * Asserts if value is not a false value, and throws if it is a true value.
             * This is added to allow for chai to be a drop-in replacement for Node's
             * assert class.
             *
             *     var err = new Error('I am a custom error');
             *     assert.ifError(err); // Rethrows err!
             *
             * @name ifError
             * @param {Object} object
             * @namespace Assert
             * @api public
             */

            assert.ifError = function (val) {
              if (val) {
                throw val
              }
            }

            /**
             * ### .isExtensible(object)
             *
             * Asserts that `object` is extensible (can have new properties added to it).
             *
             *     assert.isExtensible({});
             *
             * @name isExtensible
             * @alias extensible
             * @param {Object} object
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.isExtensible = function (obj, msg) {
              new Assertion(obj, msg, assert.isExtensible, true).to.be
                .extensible
            }

            /**
             * ### .isNotExtensible(object)
             *
             * Asserts that `object` is _not_ extensible.
             *
             *     var nonExtensibleObject = Object.preventExtensions({});
             *     var sealedObject = Object.seal({});
             *     var frozenObject = Object.freeze({});
             *
             *     assert.isNotExtensible(nonExtensibleObject);
             *     assert.isNotExtensible(sealedObject);
             *     assert.isNotExtensible(frozenObject);
             *
             * @name isNotExtensible
             * @alias notExtensible
             * @param {Object} object
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.isNotExtensible = function (obj, msg) {
              new Assertion(obj, msg, assert.isNotExtensible, true).to.not.be
                .extensible
            }

            /**
             * ### .isSealed(object)
             *
             * Asserts that `object` is sealed (cannot have new properties added to it
             * and its existing properties cannot be removed).
             *
             *     var sealedObject = Object.seal({});
             *     var frozenObject = Object.seal({});
             *
             *     assert.isSealed(sealedObject);
             *     assert.isSealed(frozenObject);
             *
             * @name isSealed
             * @alias sealed
             * @param {Object} object
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.isSealed = function (obj, msg) {
              new Assertion(obj, msg, assert.isSealed, true).to.be.sealed
            }

            /**
             * ### .isNotSealed(object)
             *
             * Asserts that `object` is _not_ sealed.
             *
             *     assert.isNotSealed({});
             *
             * @name isNotSealed
             * @alias notSealed
             * @param {Object} object
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.isNotSealed = function (obj, msg) {
              new Assertion(obj, msg, assert.isNotSealed, true).to.not.be.sealed
            }

            /**
             * ### .isFrozen(object)
             *
             * Asserts that `object` is frozen (cannot have new properties added to it
             * and its existing properties cannot be modified).
             *
             *     var frozenObject = Object.freeze({});
             *     assert.frozen(frozenObject);
             *
             * @name isFrozen
             * @alias frozen
             * @param {Object} object
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.isFrozen = function (obj, msg) {
              new Assertion(obj, msg, assert.isFrozen, true).to.be.frozen
            }

            /**
             * ### .isNotFrozen(object)
             *
             * Asserts that `object` is _not_ frozen.
             *
             *     assert.isNotFrozen({});
             *
             * @name isNotFrozen
             * @alias notFrozen
             * @param {Object} object
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.isNotFrozen = function (obj, msg) {
              new Assertion(obj, msg, assert.isNotFrozen, true).to.not.be.frozen
            }

            /**
             * ### .isEmpty(target)
             *
             * Asserts that the target does not contain any values.
             * For arrays and strings, it checks the `length` property.
             * For `Map` and `Set` instances, it checks the `size` property.
             * For non-function objects, it gets the count of own
             * enumerable string keys.
             *
             *     assert.isEmpty([]);
             *     assert.isEmpty('');
             *     assert.isEmpty(new Map);
             *     assert.isEmpty({});
             *
             * @name isEmpty
             * @alias empty
             * @param {Object|Array|String|Map|Set} target
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.isEmpty = function (val, msg) {
              new Assertion(val, msg, assert.isEmpty, true).to.be.empty
            }

            /**
             * ### .isNotEmpty(target)
             *
             * Asserts that the target contains values.
             * For arrays and strings, it checks the `length` property.
             * For `Map` and `Set` instances, it checks the `size` property.
             * For non-function objects, it gets the count of own
             * enumerable string keys.
             *
             *     assert.isNotEmpty([1, 2]);
             *     assert.isNotEmpty('34');
             *     assert.isNotEmpty(new Set([5, 6]));
             *     assert.isNotEmpty({ key: 7 });
             *
             * @name isNotEmpty
             * @alias notEmpty
             * @param {Object|Array|String|Map|Set} target
             * @param {String} message _optional_
             * @namespace Assert
             * @api public
             */

            assert.isNotEmpty = function (val, msg) {
              new Assertion(val, msg, assert.isNotEmpty, true).to.not.be.empty
            }

            /*!
             * Aliases.
             */

            ;(function alias(name, as) {
              assert[as] = assert[name]
              return alias
            })('isOk', 'ok')('isNotOk', 'notOk')('throws', 'throw')(
              'throws',
              'Throw'
            )('isExtensible', 'extensible')('isNotExtensible', 'notExtensible')(
              'isSealed',
              'sealed'
            )('isNotSealed', 'notSealed')('isFrozen', 'frozen')(
              'isNotFrozen',
              'notFrozen'
            )('isEmpty', 'empty')('isNotEmpty', 'notEmpty')
          }
        },
        {}
      ],
      7: [
        function (require, module, exports) {
          /*!
           * chai
           * Copyright(c) 2011-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          module.exports = function (chai, util) {
            chai.expect = function (val, message) {
              return new chai.Assertion(val, message)
            }

            /**
             * ### .fail([message])
             * ### .fail(actual, expected, [message], [operator])
             *
             * Throw a failure.
             *
             *     expect.fail();
             *     expect.fail("custom error message");
             *     expect.fail(1, 2);
             *     expect.fail(1, 2, "custom error message");
             *     expect.fail(1, 2, "custom error message", ">");
             *     expect.fail(1, 2, undefined, ">");
             *
             * @name fail
             * @param {Mixed} actual
             * @param {Mixed} expected
             * @param {String} message
             * @param {String} operator
             * @namespace BDD
             * @api public
             */

            chai.expect.fail = function (actual, expected, message, operator) {
              if (arguments.length < 2) {
                message = actual
                actual = undefined
              }

              message = message || 'expect.fail()'
              throw new chai.AssertionError(
                message,
                {
                  actual: actual,
                  expected: expected,
                  operator: operator
                },
                chai.expect.fail
              )
            }
          }
        },
        {}
      ],
      8: [
        function (require, module, exports) {
          /*!
           * chai
           * Copyright(c) 2011-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          module.exports = function (chai, util) {
            var Assertion = chai.Assertion

            function loadShould() {
              // explicitly define this method as function as to have it's name to include as `ssfi`
              function shouldGetter() {
                if (
                  this instanceof String ||
                  this instanceof Number ||
                  this instanceof Boolean ||
                  (typeof Symbol === 'function' && this instanceof Symbol) ||
                  (typeof BigInt === 'function' && this instanceof BigInt)
                ) {
                  return new Assertion(this.valueOf(), null, shouldGetter)
                }
                return new Assertion(this, null, shouldGetter)
              }
              function shouldSetter(value) {
                // See https://github.com/chaijs/chai/issues/86: this makes
                // `whatever.should = someValue` actually set `someValue`, which is
                // especially useful for `global.should = require('chai').should()`.
                //
                // Note that we have to use [[DefineProperty]] instead of [[Put]]
                // since otherwise we would trigger this very setter!
                Object.defineProperty(this, 'should', {
                  value: value,
                  enumerable: true,
                  configurable: true,
                  writable: true
                })
              }
              // modify Object.prototype to have `should`
              Object.defineProperty(Object.prototype, 'should', {
                set: shouldSetter,
                get: shouldGetter,
                configurable: true
              })

              var should = {}

              /**
               * ### .fail([message])
               * ### .fail(actual, expected, [message], [operator])
               *
               * Throw a failure.
               *
               *     should.fail();
               *     should.fail("custom error message");
               *     should.fail(1, 2);
               *     should.fail(1, 2, "custom error message");
               *     should.fail(1, 2, "custom error message", ">");
               *     should.fail(1, 2, undefined, ">");
               *
               *
               * @name fail
               * @param {Mixed} actual
               * @param {Mixed} expected
               * @param {String} message
               * @param {String} operator
               * @namespace BDD
               * @api public
               */

              should.fail = function (actual, expected, message, operator) {
                if (arguments.length < 2) {
                  message = actual
                  actual = undefined
                }

                message = message || 'should.fail()'
                throw new chai.AssertionError(
                  message,
                  {
                    actual: actual,
                    expected: expected,
                    operator: operator
                  },
                  should.fail
                )
              }

              /**
               * ### .equal(actual, expected, [message])
               *
               * Asserts non-strict equality (`==`) of `actual` and `expected`.
               *
               *     should.equal(3, '3', '== coerces values to strings');
               *
               * @name equal
               * @param {Mixed} actual
               * @param {Mixed} expected
               * @param {String} message
               * @namespace Should
               * @api public
               */

              should.equal = function (val1, val2, msg) {
                new Assertion(val1, msg).to.equal(val2)
              }

              /**
               * ### .throw(function, [constructor/string/regexp], [string/regexp], [message])
               *
               * Asserts that `function` will throw an error that is an instance of
               * `constructor`, or alternately that it will throw an error with message
               * matching `regexp`.
               *
               *     should.throw(fn, 'function throws a reference error');
               *     should.throw(fn, /function throws a reference error/);
               *     should.throw(fn, ReferenceError);
               *     should.throw(fn, ReferenceError, 'function throws a reference error');
               *     should.throw(fn, ReferenceError, /function throws a reference error/);
               *
               * @name throw
               * @alias Throw
               * @param {Function} function
               * @param {ErrorConstructor} constructor
               * @param {RegExp} regexp
               * @param {String} message
               * @see https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Error#Error_types
               * @namespace Should
               * @api public
               */

              should.Throw = function (fn, errt, errs, msg) {
                new Assertion(fn, msg).to.Throw(errt, errs)
              }

              /**
               * ### .exist
               *
               * Asserts that the target is neither `null` nor `undefined`.
               *
               *     var foo = 'hi';
               *
               *     should.exist(foo, 'foo exists');
               *
               * @name exist
               * @namespace Should
               * @api public
               */

              should.exist = function (val, msg) {
                new Assertion(val, msg).to.exist
              }

              // negation
              should.not = {}

              /**
               * ### .not.equal(actual, expected, [message])
               *
               * Asserts non-strict inequality (`!=`) of `actual` and `expected`.
               *
               *     should.not.equal(3, 4, 'these numbers are not equal');
               *
               * @name not.equal
               * @param {Mixed} actual
               * @param {Mixed} expected
               * @param {String} message
               * @namespace Should
               * @api public
               */

              should.not.equal = function (val1, val2, msg) {
                new Assertion(val1, msg).to.not.equal(val2)
              }

              /**
               * ### .throw(function, [constructor/regexp], [message])
               *
               * Asserts that `function` will _not_ throw an error that is an instance of
               * `constructor`, or alternately that it will not throw an error with message
               * matching `regexp`.
               *
               *     should.not.throw(fn, Error, 'function does not throw');
               *
               * @name not.throw
               * @alias not.Throw
               * @param {Function} function
               * @param {ErrorConstructor} constructor
               * @param {RegExp} regexp
               * @param {String} message
               * @see https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Error#Error_types
               * @namespace Should
               * @api public
               */

              should.not.Throw = function (fn, errt, errs, msg) {
                new Assertion(fn, msg).to.not.Throw(errt, errs)
              }

              /**
               * ### .not.exist
               *
               * Asserts that the target is neither `null` nor `undefined`.
               *
               *     var bar = null;
               *
               *     should.not.exist(bar, 'bar does not exist');
               *
               * @name not.exist
               * @namespace Should
               * @api public
               */

              should.not.exist = function (val, msg) {
                new Assertion(val, msg).to.not.exist
              }

              should['throw'] = should['Throw']
              should.not['throw'] = should.not['Throw']

              return should
            }

            chai.should = loadShould
            chai.Should = loadShould
          }
        },
        {}
      ],
      9: [
        function (require, module, exports) {
          /*!
           * Chai - addChainingMethod utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /*!
           * Module dependencies
           */

          var addLengthGuard = require('./addLengthGuard')
          var chai = require('../../chai')
          var flag = require('./flag')
          var proxify = require('./proxify')
          var transferFlags = require('./transferFlags')

          /*!
           * Module variables
           */

          // Check whether `Object.setPrototypeOf` is supported
          var canSetPrototype = typeof Object.setPrototypeOf === 'function'

          // Without `Object.setPrototypeOf` support, this module will need to add properties to a function.
          // However, some of functions' own props are not configurable and should be skipped.
          var testFn = function () {}
          var excludeNames = Object.getOwnPropertyNames(testFn).filter(
            function (name) {
              var propDesc = Object.getOwnPropertyDescriptor(testFn, name)

              // Note: PhantomJS 1.x includes `callee` as one of `testFn`'s own properties,
              // but then returns `undefined` as the property descriptor for `callee`. As a
              // workaround, we perform an otherwise unnecessary type-check for `propDesc`,
              // and then filter it out if it's not an object as it should be.
              if (typeof propDesc !== 'object') return true

              return !propDesc.configurable
            }
          )

          // Cache `Function` properties
          var call = Function.prototype.call,
            apply = Function.prototype.apply

          /**
           * ### .addChainableMethod(ctx, name, method, chainingBehavior)
           *
           * Adds a method to an object, such that the method can also be chained.
           *
           *     utils.addChainableMethod(chai.Assertion.prototype, 'foo', function (str) {
           *       var obj = utils.flag(this, 'object');
           *       new chai.Assertion(obj).to.be.equal(str);
           *     });
           *
           * Can also be accessed directly from `chai.Assertion`.
           *
           *     chai.Assertion.addChainableMethod('foo', fn, chainingBehavior);
           *
           * The result can then be used as both a method assertion, executing both `method` and
           * `chainingBehavior`, or as a language chain, which only executes `chainingBehavior`.
           *
           *     expect(fooStr).to.be.foo('bar');
           *     expect(fooStr).to.be.foo.equal('foo');
           *
           * @param {Object} ctx object to which the method is added
           * @param {String} name of method to add
           * @param {Function} method function to be used for `name`, when called
           * @param {Function} chainingBehavior function to be called every time the property is accessed
           * @namespace Utils
           * @name addChainableMethod
           * @api public
           */

          module.exports = function addChainableMethod(
            ctx,
            name,
            method,
            chainingBehavior
          ) {
            if (typeof chainingBehavior !== 'function') {
              chainingBehavior = function () {}
            }

            var chainableBehavior = {
              method: method,
              chainingBehavior: chainingBehavior
            }

            // save the methods so we can overwrite them later, if we need to.
            if (!ctx.__methods) {
              ctx.__methods = {}
            }
            ctx.__methods[name] = chainableBehavior

            Object.defineProperty(ctx, name, {
              get: function chainableMethodGetter() {
                chainableBehavior.chainingBehavior.call(this)

                var chainableMethodWrapper = function () {
                  // Setting the `ssfi` flag to `chainableMethodWrapper` causes this
                  // function to be the starting point for removing implementation
                  // frames from the stack trace of a failed assertion.
                  //
                  // However, we only want to use this function as the starting point if
                  // the `lockSsfi` flag isn't set.
                  //
                  // If the `lockSsfi` flag is set, then this assertion is being
                  // invoked from inside of another assertion. In this case, the `ssfi`
                  // flag has already been set by the outer assertion.
                  //
                  // Note that overwriting a chainable method merely replaces the saved
                  // methods in `ctx.__methods` instead of completely replacing the
                  // overwritten assertion. Therefore, an overwriting assertion won't
                  // set the `ssfi` or `lockSsfi` flags.
                  if (!flag(this, 'lockSsfi')) {
                    flag(this, 'ssfi', chainableMethodWrapper)
                  }

                  var result = chainableBehavior.method.apply(this, arguments)
                  if (result !== undefined) {
                    return result
                  }

                  var newAssertion = new chai.Assertion()
                  transferFlags(this, newAssertion)
                  return newAssertion
                }

                addLengthGuard(chainableMethodWrapper, name, true)

                // Use `Object.setPrototypeOf` if available
                if (canSetPrototype) {
                  // Inherit all properties from the object by replacing the `Function` prototype
                  var prototype = Object.create(this)
                  // Restore the `call` and `apply` methods from `Function`
                  prototype.call = call
                  prototype.apply = apply
                  Object.setPrototypeOf(chainableMethodWrapper, prototype)
                }
                // Otherwise, redefine all properties (slow!)
                else {
                  var asserterNames = Object.getOwnPropertyNames(ctx)
                  asserterNames.forEach(function (asserterName) {
                    if (excludeNames.indexOf(asserterName) !== -1) {
                      return
                    }

                    var pd = Object.getOwnPropertyDescriptor(ctx, asserterName)
                    Object.defineProperty(
                      chainableMethodWrapper,
                      asserterName,
                      pd
                    )
                  })
                }

                transferFlags(this, chainableMethodWrapper)
                return proxify(chainableMethodWrapper)
              },
              configurable: true
            })
          }
        },
        {
          '../../chai': 2,
          './addLengthGuard': 10,
          './flag': 15,
          './proxify': 31,
          './transferFlags': 33
        }
      ],
      10: [
        function (require, module, exports) {
          var fnLengthDesc = Object.getOwnPropertyDescriptor(function () {},
          'length')

          /*!
           * Chai - addLengthGuard utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .addLengthGuard(fn, assertionName, isChainable)
           *
           * Define `length` as a getter on the given uninvoked method assertion. The
           * getter acts as a guard against chaining `length` directly off of an uninvoked
           * method assertion, which is a problem because it references `function`'s
           * built-in `length` property instead of Chai's `length` assertion. When the
           * getter catches the user making this mistake, it throws an error with a
           * helpful message.
           *
           * There are two ways in which this mistake can be made. The first way is by
           * chaining the `length` assertion directly off of an uninvoked chainable
           * method. In this case, Chai suggests that the user use `lengthOf` instead. The
           * second way is by chaining the `length` assertion directly off of an uninvoked
           * non-chainable method. Non-chainable methods must be invoked prior to
           * chaining. In this case, Chai suggests that the user consult the docs for the
           * given assertion.
           *
           * If the `length` property of functions is unconfigurable, then return `fn`
           * without modification.
           *
           * Note that in ES6, the function's `length` property is configurable, so once
           * support for legacy environments is dropped, Chai's `length` property can
           * replace the built-in function's `length` property, and this length guard will
           * no longer be necessary. In the mean time, maintaining consistency across all
           * environments is the priority.
           *
           * @param {Function} fn
           * @param {String} assertionName
           * @param {Boolean} isChainable
           * @namespace Utils
           * @name addLengthGuard
           */

          module.exports = function addLengthGuard(
            fn,
            assertionName,
            isChainable
          ) {
            if (!fnLengthDesc.configurable) return fn

            Object.defineProperty(fn, 'length', {
              get: function () {
                if (isChainable) {
                  throw Error(
                    'Invalid Chai property: ' +
                      assertionName +
                      '.length. Due' +
                      ' to a compatibility issue, "length" cannot directly follow "' +
                      assertionName +
                      '". Use "' +
                      assertionName +
                      '.lengthOf" instead.'
                  )
                }

                throw Error(
                  'Invalid Chai property: ' +
                    assertionName +
                    '.length. See' +
                    ' docs for proper usage of "' +
                    assertionName +
                    '".'
                )
              }
            })

            return fn
          }
        },
        {}
      ],
      11: [
        function (require, module, exports) {
          /*!
           * Chai - addMethod utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          var addLengthGuard = require('./addLengthGuard')
          var chai = require('../../chai')
          var flag = require('./flag')
          var proxify = require('./proxify')
          var transferFlags = require('./transferFlags')

          /**
           * ### .addMethod(ctx, name, method)
           *
           * Adds a method to the prototype of an object.
           *
           *     utils.addMethod(chai.Assertion.prototype, 'foo', function (str) {
           *       var obj = utils.flag(this, 'object');
           *       new chai.Assertion(obj).to.be.equal(str);
           *     });
           *
           * Can also be accessed directly from `chai.Assertion`.
           *
           *     chai.Assertion.addMethod('foo', fn);
           *
           * Then can be used as any other assertion.
           *
           *     expect(fooStr).to.be.foo('bar');
           *
           * @param {Object} ctx object to which the method is added
           * @param {String} name of method to add
           * @param {Function} method function to be used for name
           * @namespace Utils
           * @name addMethod
           * @api public
           */

          module.exports = function addMethod(ctx, name, method) {
            var methodWrapper = function () {
              // Setting the `ssfi` flag to `methodWrapper` causes this function to be the
              // starting point for removing implementation frames from the stack trace of
              // a failed assertion.
              //
              // However, we only want to use this function as the starting point if the
              // `lockSsfi` flag isn't set.
              //
              // If the `lockSsfi` flag is set, then either this assertion has been
              // overwritten by another assertion, or this assertion is being invoked from
              // inside of another assertion. In the first case, the `ssfi` flag has
              // already been set by the overwriting assertion. In the second case, the
              // `ssfi` flag has already been set by the outer assertion.
              if (!flag(this, 'lockSsfi')) {
                flag(this, 'ssfi', methodWrapper)
              }

              var result = method.apply(this, arguments)
              if (result !== undefined) return result

              var newAssertion = new chai.Assertion()
              transferFlags(this, newAssertion)
              return newAssertion
            }

            addLengthGuard(methodWrapper, name, false)
            ctx[name] = proxify(methodWrapper, name)
          }
        },
        {
          '../../chai': 2,
          './addLengthGuard': 10,
          './flag': 15,
          './proxify': 31,
          './transferFlags': 33
        }
      ],
      12: [
        function (require, module, exports) {
          /*!
           * Chai - addProperty utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          var chai = require('../../chai')
          var flag = require('./flag')
          var isProxyEnabled = require('./isProxyEnabled')
          var transferFlags = require('./transferFlags')

          /**
           * ### .addProperty(ctx, name, getter)
           *
           * Adds a property to the prototype of an object.
           *
           *     utils.addProperty(chai.Assertion.prototype, 'foo', function () {
           *       var obj = utils.flag(this, 'object');
           *       new chai.Assertion(obj).to.be.instanceof(Foo);
           *     });
           *
           * Can also be accessed directly from `chai.Assertion`.
           *
           *     chai.Assertion.addProperty('foo', fn);
           *
           * Then can be used as any other assertion.
           *
           *     expect(myFoo).to.be.foo;
           *
           * @param {Object} ctx object to which the property is added
           * @param {String} name of property to add
           * @param {Function} getter function to be used for name
           * @namespace Utils
           * @name addProperty
           * @api public
           */

          module.exports = function addProperty(ctx, name, getter) {
            getter = getter === undefined ? function () {} : getter

            Object.defineProperty(ctx, name, {
              get: function propertyGetter() {
                // Setting the `ssfi` flag to `propertyGetter` causes this function to
                // be the starting point for removing implementation frames from the
                // stack trace of a failed assertion.
                //
                // However, we only want to use this function as the starting point if
                // the `lockSsfi` flag isn't set and proxy protection is disabled.
                //
                // If the `lockSsfi` flag is set, then either this assertion has been
                // overwritten by another assertion, or this assertion is being invoked
                // from inside of another assertion. In the first case, the `ssfi` flag
                // has already been set by the overwriting assertion. In the second
                // case, the `ssfi` flag has already been set by the outer assertion.
                //
                // If proxy protection is enabled, then the `ssfi` flag has already been
                // set by the proxy getter.
                if (!isProxyEnabled() && !flag(this, 'lockSsfi')) {
                  flag(this, 'ssfi', propertyGetter)
                }

                var result = getter.call(this)
                if (result !== undefined) return result

                var newAssertion = new chai.Assertion()
                transferFlags(this, newAssertion)
                return newAssertion
              },
              configurable: true
            })
          }
        },
        {
          '../../chai': 2,
          './flag': 15,
          './isProxyEnabled': 26,
          './transferFlags': 33
        }
      ],
      13: [
        function (require, module, exports) {
          /*!
           * Chai - compareByInspect utility
           * Copyright(c) 2011-2016 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /*!
           * Module dependencies
           */

          var inspect = require('./inspect')

          /**
           * ### .compareByInspect(mixed, mixed)
           *
           * To be used as a compareFunction with Array.prototype.sort. Compares elements
           * using inspect instead of default behavior of using toString so that Symbols
           * and objects with irregular/missing toString can still be sorted without a
           * TypeError.
           *
           * @param {Mixed} first element to compare
           * @param {Mixed} second element to compare
           * @returns {Number} -1 if 'a' should come before 'b'; otherwise 1
           * @name compareByInspect
           * @namespace Utils
           * @api public
           */

          module.exports = function compareByInspect(a, b) {
            return inspect(a) < inspect(b) ? -1 : 1
          }
        },
        { './inspect': 24 }
      ],
      14: [
        function (require, module, exports) {
          /*!
           * Chai - expectTypes utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .expectTypes(obj, types)
           *
           * Ensures that the object being tested against is of a valid type.
           *
           *     utils.expectTypes(this, ['array', 'object', 'string']);
           *
           * @param {Mixed} obj constructed Assertion
           * @param {Array} type A list of allowed types for this assertion
           * @namespace Utils
           * @name expectTypes
           * @api public
           */

          var AssertionError = require('assertion-error')
          var flag = require('./flag')
          var type = require('type-detect')

          module.exports = function expectTypes(obj, types) {
            var flagMsg = flag(obj, 'message')
            var ssfi = flag(obj, 'ssfi')

            flagMsg = flagMsg ? flagMsg + ': ' : ''

            obj = flag(obj, 'object')
            types = types.map(function (t) {
              return t.toLowerCase()
            })
            types.sort()

            // Transforms ['lorem', 'ipsum'] into 'a lorem, or an ipsum'
            var str = types
              .map(function (t, index) {
                var art = ~['a', 'e', 'i', 'o', 'u'].indexOf(t.charAt(0))
                  ? 'an'
                  : 'a'
                var or =
                  types.length > 1 && index === types.length - 1 ? 'or ' : ''
                return or + art + ' ' + t
              })
              .join(', ')

            var objType = type(obj).toLowerCase()

            if (
              !types.some(function (expected) {
                return objType === expected
              })
            ) {
              throw new AssertionError(
                flagMsg +
                  'object tested must be ' +
                  str +
                  ', but ' +
                  objType +
                  ' given',
                undefined,
                ssfi
              )
            }
          }
        },
        { './flag': 15, 'assertion-error': 34, 'type-detect': 39 }
      ],
      15: [
        function (require, module, exports) {
          /*!
           * Chai - flag utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .flag(object, key, [value])
           *
           * Get or set a flag value on an object. If a
           * value is provided it will be set, else it will
           * return the currently set value or `undefined` if
           * the value is not set.
           *
           *     utils.flag(this, 'foo', 'bar'); // setter
           *     utils.flag(this, 'foo'); // getter, returns `bar`
           *
           * @param {Object} object constructed Assertion
           * @param {String} key
           * @param {Mixed} value (optional)
           * @namespace Utils
           * @name flag
           * @api private
           */

          module.exports = function flag(obj, key, value) {
            var flags = obj.__flags || (obj.__flags = Object.create(null))
            if (arguments.length === 3) {
              flags[key] = value
            } else {
              return flags[key]
            }
          }
        },
        {}
      ],
      16: [
        function (require, module, exports) {
          /*!
           * Chai - getActual utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .getActual(object, [actual])
           *
           * Returns the `actual` value for an Assertion.
           *
           * @param {Object} object (constructed Assertion)
           * @param {Arguments} chai.Assertion.prototype.assert arguments
           * @namespace Utils
           * @name getActual
           */

          module.exports = function getActual(obj, args) {
            return args.length > 4 ? args[4] : obj._obj
          }
        },
        {}
      ],
      17: [
        function (require, module, exports) {
          /*!
           * Chai - getEnumerableProperties utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .getEnumerableProperties(object)
           *
           * This allows the retrieval of enumerable property names of an object,
           * inherited or not.
           *
           * @param {Object} object
           * @returns {Array}
           * @namespace Utils
           * @name getEnumerableProperties
           * @api public
           */

          module.exports = function getEnumerableProperties(object) {
            var result = []
            for (var name in object) {
              result.push(name)
            }
            return result
          }
        },
        {}
      ],
      18: [
        function (require, module, exports) {
          /*!
           * Chai - message composition utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /*!
           * Module dependencies
           */

          var flag = require('./flag'),
            getActual = require('./getActual'),
            objDisplay = require('./objDisplay')

          /**
           * ### .getMessage(object, message, negateMessage)
           *
           * Construct the error message based on flags
           * and template tags. Template tags will return
           * a stringified inspection of the object referenced.
           *
           * Message template tags:
           * - `#{this}` current asserted object
           * - `#{act}` actual value
           * - `#{exp}` expected value
           *
           * @param {Object} object (constructed Assertion)
           * @param {Arguments} chai.Assertion.prototype.assert arguments
           * @namespace Utils
           * @name getMessage
           * @api public
           */

          module.exports = function getMessage(obj, args) {
            var negate = flag(obj, 'negate'),
              val = flag(obj, 'object'),
              expected = args[3],
              actual = getActual(obj, args),
              msg = negate ? args[2] : args[1],
              flagMsg = flag(obj, 'message')

            if (typeof msg === 'function') msg = msg()
            msg = msg || ''
            msg = msg
              .replace(/#\{this\}/g, function () {
                return objDisplay(val)
              })
              .replace(/#\{act\}/g, function () {
                return objDisplay(actual)
              })
              .replace(/#\{exp\}/g, function () {
                return objDisplay(expected)
              })

            return flagMsg ? flagMsg + ': ' + msg : msg
          }
        },
        { './flag': 15, './getActual': 16, './objDisplay': 27 }
      ],
      19: [
        function (require, module, exports) {
          var type = require('type-detect')

          var flag = require('./flag')

          function isObjectType(obj) {
            var objectType = type(obj)
            var objectTypes = ['Array', 'Object', 'function']

            return objectTypes.indexOf(objectType) !== -1
          }

          /**
           * ### .getOperator(message)
           *
           * Extract the operator from error message.
           * Operator defined is based on below link
           * https://nodejs.org/api/assert.html#assert_assert.
           *
           * Returns the `operator` or `undefined` value for an Assertion.
           *
           * @param {Object} object (constructed Assertion)
           * @param {Arguments} chai.Assertion.prototype.assert arguments
           * @namespace Utils
           * @name getOperator
           * @api public
           */

          module.exports = function getOperator(obj, args) {
            var operator = flag(obj, 'operator')
            var negate = flag(obj, 'negate')
            var expected = args[3]
            var msg = negate ? args[2] : args[1]

            if (operator) {
              return operator
            }

            if (typeof msg === 'function') msg = msg()

            msg = msg || ''
            if (!msg) {
              return undefined
            }

            if (/\shave\s/.test(msg)) {
              return undefined
            }

            var isObject = isObjectType(expected)
            if (/\snot\s/.test(msg)) {
              return isObject ? 'notDeepStrictEqual' : 'notStrictEqual'
            }

            return isObject ? 'deepStrictEqual' : 'strictEqual'
          }
        },
        { './flag': 15, 'type-detect': 39 }
      ],
      20: [
        function (require, module, exports) {
          /*!
           * Chai - getOwnEnumerableProperties utility
           * Copyright(c) 2011-2016 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /*!
           * Module dependencies
           */

          var getOwnEnumerablePropertySymbols = require('./getOwnEnumerablePropertySymbols')

          /**
           * ### .getOwnEnumerableProperties(object)
           *
           * This allows the retrieval of directly-owned enumerable property names and
           * symbols of an object. This function is necessary because Object.keys only
           * returns enumerable property names, not enumerable property symbols.
           *
           * @param {Object} object
           * @returns {Array}
           * @namespace Utils
           * @name getOwnEnumerableProperties
           * @api public
           */

          module.exports = function getOwnEnumerableProperties(obj) {
            return Object.keys(obj).concat(getOwnEnumerablePropertySymbols(obj))
          }
        },
        { './getOwnEnumerablePropertySymbols': 21 }
      ],
      21: [
        function (require, module, exports) {
          /*!
           * Chai - getOwnEnumerablePropertySymbols utility
           * Copyright(c) 2011-2016 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .getOwnEnumerablePropertySymbols(object)
           *
           * This allows the retrieval of directly-owned enumerable property symbols of an
           * object. This function is necessary because Object.getOwnPropertySymbols
           * returns both enumerable and non-enumerable property symbols.
           *
           * @param {Object} object
           * @returns {Array}
           * @namespace Utils
           * @name getOwnEnumerablePropertySymbols
           * @api public
           */

          module.exports = function getOwnEnumerablePropertySymbols(obj) {
            if (typeof Object.getOwnPropertySymbols !== 'function') return []

            return Object.getOwnPropertySymbols(obj).filter(function (sym) {
              return Object.getOwnPropertyDescriptor(obj, sym).enumerable
            })
          }
        },
        {}
      ],
      22: [
        function (require, module, exports) {
          /*!
           * Chai - getProperties utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .getProperties(object)
           *
           * This allows the retrieval of property names of an object, enumerable or not,
           * inherited or not.
           *
           * @param {Object} object
           * @returns {Array}
           * @namespace Utils
           * @name getProperties
           * @api public
           */

          module.exports = function getProperties(object) {
            var result = Object.getOwnPropertyNames(object)

            function addProperty(property) {
              if (result.indexOf(property) === -1) {
                result.push(property)
              }
            }

            var proto = Object.getPrototypeOf(object)
            while (proto !== null) {
              Object.getOwnPropertyNames(proto).forEach(addProperty)
              proto = Object.getPrototypeOf(proto)
            }

            return result
          }
        },
        {}
      ],
      23: [
        function (require, module, exports) {
          /*!
           * chai
           * Copyright(c) 2011 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /*!
           * Dependencies that are used for multiple exports are required here only once
           */

          var pathval = require('pathval')

          /*!
           * test utility
           */

          exports.test = require('./test')

          /*!
           * type utility
           */

          exports.type = require('type-detect')

          /*!
           * expectTypes utility
           */
          exports.expectTypes = require('./expectTypes')

          /*!
           * message utility
           */

          exports.getMessage = require('./getMessage')

          /*!
           * actual utility
           */

          exports.getActual = require('./getActual')

          /*!
           * Inspect util
           */

          exports.inspect = require('./inspect')

          /*!
           * Object Display util
           */

          exports.objDisplay = require('./objDisplay')

          /*!
           * Flag utility
           */

          exports.flag = require('./flag')

          /*!
           * Flag transferring utility
           */

          exports.transferFlags = require('./transferFlags')

          /*!
           * Deep equal utility
           */

          exports.eql = require('deep-eql')

          /*!
           * Deep path info
           */

          exports.getPathInfo = pathval.getPathInfo

          /*!
           * Check if a property exists
           */

          exports.hasProperty = pathval.hasProperty

          /*!
           * Function name
           */

          exports.getName = require('get-func-name')

          /*!
           * add Property
           */

          exports.addProperty = require('./addProperty')

          /*!
           * add Method
           */

          exports.addMethod = require('./addMethod')

          /*!
           * overwrite Property
           */

          exports.overwriteProperty = require('./overwriteProperty')

          /*!
           * overwrite Method
           */

          exports.overwriteMethod = require('./overwriteMethod')

          /*!
           * Add a chainable method
           */

          exports.addChainableMethod = require('./addChainableMethod')

          /*!
           * Overwrite chainable method
           */

          exports.overwriteChainableMethod = require('./overwriteChainableMethod')

          /*!
           * Compare by inspect method
           */

          exports.compareByInspect = require('./compareByInspect')

          /*!
           * Get own enumerable property symbols method
           */

          exports.getOwnEnumerablePropertySymbols = require('./getOwnEnumerablePropertySymbols')

          /*!
           * Get own enumerable properties method
           */

          exports.getOwnEnumerableProperties = require('./getOwnEnumerableProperties')

          /*!
           * Checks error against a given set of criteria
           */

          exports.checkError = require('check-error')

          /*!
           * Proxify util
           */

          exports.proxify = require('./proxify')

          /*!
           * addLengthGuard util
           */

          exports.addLengthGuard = require('./addLengthGuard')

          /*!
           * isProxyEnabled helper
           */

          exports.isProxyEnabled = require('./isProxyEnabled')

          /*!
           * isNaN method
           */

          exports.isNaN = require('./isNaN')

          /*!
           * getOperator method
           */

          exports.getOperator = require('./getOperator')
        },
        {
          './addChainableMethod': 9,
          './addLengthGuard': 10,
          './addMethod': 11,
          './addProperty': 12,
          './compareByInspect': 13,
          './expectTypes': 14,
          './flag': 15,
          './getActual': 16,
          './getMessage': 18,
          './getOperator': 19,
          './getOwnEnumerableProperties': 20,
          './getOwnEnumerablePropertySymbols': 21,
          './inspect': 24,
          './isNaN': 25,
          './isProxyEnabled': 26,
          './objDisplay': 27,
          './overwriteChainableMethod': 28,
          './overwriteMethod': 29,
          './overwriteProperty': 30,
          './proxify': 31,
          './test': 32,
          './transferFlags': 33,
          'check-error': 35,
          'deep-eql': 36,
          'get-func-name': 37,
          pathval: 38,
          'type-detect': 39
        }
      ],
      24: [
        function (require, module, exports) {
          // This is (almost) directly from Node.js utils
          // https://github.com/joyent/node/blob/f8c335d0caf47f16d31413f89aa28eda3878e3aa/lib/util.js

          var getName = require('get-func-name')
          var getProperties = require('./getProperties')
          var getEnumerableProperties = require('./getEnumerableProperties')
          var config = require('../config')

          module.exports = inspect

          /**
           * ### .inspect(obj, [showHidden], [depth], [colors])
           *
           * Echoes the value of a value. Tries to print the value out
           * in the best way possible given the different types.
           *
           * @param {Object} obj The object to print out.
           * @param {Boolean} showHidden Flag that shows hidden (not enumerable)
           *    properties of objects. Default is false.
           * @param {Number} depth Depth in which to descend in object. Default is 2.
           * @param {Boolean} colors Flag to turn on ANSI escape codes to color the
           *    output. Default is false (no coloring).
           * @namespace Utils
           * @name inspect
           */
          function inspect(obj, showHidden, depth, colors) {
            var ctx = {
              showHidden: showHidden,
              seen: [],
              stylize: function (str) {
                return str
              }
            }
            return formatValue(
              ctx,
              obj,
              typeof depth === 'undefined' ? 2 : depth
            )
          }

          // Returns true if object is a DOM element.
          var isDOMElement = function (object) {
            if (typeof HTMLElement === 'object') {
              return object instanceof HTMLElement
            } else {
              return (
                object &&
                typeof object === 'object' &&
                'nodeType' in object &&
                object.nodeType === 1 &&
                typeof object.nodeName === 'string'
              )
            }
          }

          function formatValue(ctx, value, recurseTimes) {
            // Provide a hook for user-specified inspect functions.
            // Check that value is an object with an inspect function on it
            if (
              value &&
              typeof value.inspect === 'function' &&
              // Filter out the util module, it's inspect function is special
              value.inspect !== exports.inspect &&
              // Also filter out any prototype objects using the circular check.
              !(value.constructor && value.constructor.prototype === value)
            ) {
              var ret = value.inspect(recurseTimes, ctx)
              if (typeof ret !== 'string') {
                ret = formatValue(ctx, ret, recurseTimes)
              }
              return ret
            }

            // Primitive types cannot have properties
            var primitive = formatPrimitive(ctx, value)
            if (primitive) {
              return primitive
            }

            // If this is a DOM element, try to get the outer HTML.
            if (isDOMElement(value)) {
              if ('outerHTML' in value) {
                return value.outerHTML
                // This value does not have an outerHTML attribute,
                //   it could still be an XML element
              } else {
                // Attempt to serialize it
                try {
                  if (document.xmlVersion) {
                    var xmlSerializer = new XMLSerializer()
                    return xmlSerializer.serializeToString(value)
                  } else {
                    // Firefox 11- do not support outerHTML
                    //   It does, however, support innerHTML
                    //   Use the following to render the element
                    var ns = 'http://www.w3.org/1999/xhtml'
                    var container = document.createElementNS(ns, '_')

                    container.appendChild(value.cloneNode(false))
                    var html = container.innerHTML.replace(
                      '><',
                      '>' + value.innerHTML + '<'
                    )
                    container.innerHTML = ''
                    return html
                  }
                } catch (err) {
                  // This could be a non-native DOM implementation,
                  //   continue with the normal flow:
                  //   printing the element as if it is an object.
                }
              }
            }

            // Look up the keys of the object.
            var visibleKeys = getEnumerableProperties(value)
            var keys = ctx.showHidden ? getProperties(value) : visibleKeys

            var name, nameSuffix

            // Some type of object without properties can be shortcut.
            // In IE, errors have a single `stack` property, or if they are vanilla `Error`,
            // a `stack` plus `description` property; ignore those for consistency.
            if (
              keys.length === 0 ||
              (isError(value) &&
                ((keys.length === 1 && keys[0] === 'stack') ||
                  (keys.length === 2 &&
                    keys[0] === 'description' &&
                    keys[1] === 'stack')))
            ) {
              if (typeof value === 'function') {
                name = getName(value)
                nameSuffix = name ? ': ' + name : ''
                return ctx.stylize('[Function' + nameSuffix + ']', 'special')
              }
              if (isRegExp(value)) {
                return ctx.stylize(
                  RegExp.prototype.toString.call(value),
                  'regexp'
                )
              }
              if (isDate(value)) {
                return ctx.stylize(
                  Date.prototype.toUTCString.call(value),
                  'date'
                )
              }
              if (isError(value)) {
                return formatError(value)
              }
            }

            var base = '',
              array = false,
              typedArray = false,
              braces = ['{', '}']

            if (isTypedArray(value)) {
              typedArray = true
              braces = ['[', ']']
            }

            // Make Array say that they are Array
            if (isArray(value)) {
              array = true
              braces = ['[', ']']
            }

            // Make functions say that they are functions
            if (typeof value === 'function') {
              name = getName(value)
              nameSuffix = name ? ': ' + name : ''
              base = ' [Function' + nameSuffix + ']'
            }

            // Make RegExps say that they are RegExps
            if (isRegExp(value)) {
              base = ' ' + RegExp.prototype.toString.call(value)
            }

            // Make dates with properties first say the date
            if (isDate(value)) {
              base = ' ' + Date.prototype.toUTCString.call(value)
            }

            // Make error with message first say the error
            if (isError(value)) {
              return formatError(value)
            }

            if (keys.length === 0 && (!array || value.length == 0)) {
              return braces[0] + base + braces[1]
            }

            if (recurseTimes < 0) {
              if (isRegExp(value)) {
                return ctx.stylize(
                  RegExp.prototype.toString.call(value),
                  'regexp'
                )
              } else {
                return ctx.stylize('[Object]', 'special')
              }
            }

            ctx.seen.push(value)

            var output
            if (array) {
              output = formatArray(ctx, value, recurseTimes, visibleKeys, keys)
            } else if (typedArray) {
              return formatTypedArray(value)
            } else {
              output = keys.map(function (key) {
                return formatProperty(
                  ctx,
                  value,
                  recurseTimes,
                  visibleKeys,
                  key,
                  array
                )
              })
            }

            ctx.seen.pop()

            return reduceToSingleString(output, base, braces)
          }

          function formatPrimitive(ctx, value) {
            switch (typeof value) {
              case 'undefined':
                return ctx.stylize('undefined', 'undefined')

              case 'string':
                var simple =
                  "'" +
                  JSON.stringify(value)
                    .replace(/^"|"$/g, '')
                    .replace(/'/g, "\\'")
                    .replace(/\\"/g, '"') +
                  "'"
                return ctx.stylize(simple, 'string')

              case 'number':
                if (value === 0 && 1 / value === -Infinity) {
                  return ctx.stylize('-0', 'number')
                }
                return ctx.stylize('' + value, 'number')

              case 'boolean':
                return ctx.stylize('' + value, 'boolean')

              case 'symbol':
                return ctx.stylize(value.toString(), 'symbol')

              case 'bigint':
                return ctx.stylize(value.toString() + 'n', 'bigint')
            }
            // For some reason typeof null is "object", so special case here.
            if (value === null) {
              return ctx.stylize('null', 'null')
            }
          }

          function formatError(value) {
            return '[' + Error.prototype.toString.call(value) + ']'
          }

          function formatArray(ctx, value, recurseTimes, visibleKeys, keys) {
            var output = []
            for (var i = 0, l = value.length; i < l; ++i) {
              if (Object.prototype.hasOwnProperty.call(value, String(i))) {
                output.push(
                  formatProperty(
                    ctx,
                    value,
                    recurseTimes,
                    visibleKeys,
                    String(i),
                    true
                  )
                )
              } else {
                output.push('')
              }
            }

            keys.forEach(function (key) {
              if (!key.match(/^\d+$/)) {
                output.push(
                  formatProperty(
                    ctx,
                    value,
                    recurseTimes,
                    visibleKeys,
                    key,
                    true
                  )
                )
              }
            })
            return output
          }

          function formatTypedArray(value) {
            var str = '[ '

            for (var i = 0; i < value.length; ++i) {
              if (str.length >= config.truncateThreshold - 7) {
                str += '...'
                break
              }
              str += value[i] + ', '
            }
            str += ' ]'

            // Removing trailing `, ` if the array was not truncated
            if (str.indexOf(',  ]') !== -1) {
              str = str.replace(',  ]', ' ]')
            }

            return str
          }

          function formatProperty(
            ctx,
            value,
            recurseTimes,
            visibleKeys,
            key,
            array
          ) {
            var name
            var propDescriptor = Object.getOwnPropertyDescriptor(value, key)
            var str

            if (propDescriptor) {
              if (propDescriptor.get) {
                if (propDescriptor.set) {
                  str = ctx.stylize('[Getter/Setter]', 'special')
                } else {
                  str = ctx.stylize('[Getter]', 'special')
                }
              } else {
                if (propDescriptor.set) {
                  str = ctx.stylize('[Setter]', 'special')
                }
              }
            }
            if (visibleKeys.indexOf(key) < 0) {
              name = '[' + key + ']'
            }
            if (!str) {
              if (ctx.seen.indexOf(value[key]) < 0) {
                if (recurseTimes === null) {
                  str = formatValue(ctx, value[key], null)
                } else {
                  str = formatValue(ctx, value[key], recurseTimes - 1)
                }
                if (str.indexOf('\n') > -1) {
                  if (array) {
                    str = str
                      .split('\n')
                      .map(function (line) {
                        return '  ' + line
                      })
                      .join('\n')
                      .substr(2)
                  } else {
                    str =
                      '\n' +
                      str
                        .split('\n')
                        .map(function (line) {
                          return '   ' + line
                        })
                        .join('\n')
                  }
                }
              } else {
                str = ctx.stylize('[Circular]', 'special')
              }
            }
            if (typeof name === 'undefined') {
              if (array && key.match(/^\d+$/)) {
                return str
              }
              name = JSON.stringify('' + key)
              if (name.match(/^"([a-zA-Z_][a-zA-Z_0-9]*)"$/)) {
                name = name.substr(1, name.length - 2)
                name = ctx.stylize(name, 'name')
              } else {
                name = name
                  .replace(/'/g, "\\'")
                  .replace(/\\"/g, '"')
                  .replace(/(^"|"$)/g, "'")
                name = ctx.stylize(name, 'string')
              }
            }

            return name + ': ' + str
          }

          function reduceToSingleString(output, base, braces) {
            var length = output.reduce(function (prev, cur) {
              return prev + cur.length + 1
            }, 0)

            if (length > 60) {
              return (
                braces[0] +
                (base === '' ? '' : base + '\n ') +
                ' ' +
                output.join(',\n  ') +
                ' ' +
                braces[1]
              )
            }

            return braces[0] + base + ' ' + output.join(', ') + ' ' + braces[1]
          }

          function isTypedArray(ar) {
            // Unfortunately there's no way to check if an object is a TypedArray
            // We have to check if it's one of these types
            return (
              typeof ar === 'object' && /\w+Array]$/.test(objectToString(ar))
            )
          }

          function isArray(ar) {
            return (
              Array.isArray(ar) ||
              (typeof ar === 'object' &&
                objectToString(ar) === '[object Array]')
            )
          }

          function isRegExp(re) {
            return (
              typeof re === 'object' && objectToString(re) === '[object RegExp]'
            )
          }

          function isDate(d) {
            return (
              typeof d === 'object' && objectToString(d) === '[object Date]'
            )
          }

          function isError(e) {
            return (
              typeof e === 'object' && objectToString(e) === '[object Error]'
            )
          }

          function objectToString(o) {
            return Object.prototype.toString.call(o)
          }
        },
        {
          '../config': 4,
          './getEnumerableProperties': 17,
          './getProperties': 22,
          'get-func-name': 37
        }
      ],
      25: [
        function (require, module, exports) {
          /*!
           * Chai - isNaN utility
           * Copyright(c) 2012-2015 Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
           * MIT Licensed
           */

          /**
           * ### .isNaN(value)
           *
           * Checks if the given value is NaN or not.
           *
           *     utils.isNaN(NaN); // true
           *
           * @param {Value} The value which has to be checked if it is NaN
           * @name isNaN
           * @api private
           */

          function isNaN(value) {
            // Refer http://www.ecma-international.org/ecma-262/6.0/#sec-isnan-number
            // section's NOTE.
            return value !== value
          }

          // If ECMAScript 6's Number.isNaN is present, prefer that.
          module.exports = Number.isNaN || isNaN
        },
        {}
      ],
      26: [
        function (require, module, exports) {
          var config = require('../config')

          /*!
           * Chai - isProxyEnabled helper
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .isProxyEnabled()
           *
           * Helper function to check if Chai's proxy protection feature is enabled. If
           * proxies are unsupported or disabled via the user's Chai config, then return
           * false. Otherwise, return true.
           *
           * @namespace Utils
           * @name isProxyEnabled
           */

          module.exports = function isProxyEnabled() {
            return (
              config.useProxy &&
              typeof Proxy !== 'undefined' &&
              typeof Reflect !== 'undefined'
            )
          }
        },
        { '../config': 4 }
      ],
      27: [
        function (require, module, exports) {
          /*!
           * Chai - flag utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /*!
           * Module dependencies
           */

          var inspect = require('./inspect')
          var config = require('../config')

          /**
           * ### .objDisplay(object)
           *
           * Determines if an object or an array matches
           * criteria to be inspected in-line for error
           * messages or should be truncated.
           *
           * @param {Mixed} javascript object to inspect
           * @name objDisplay
           * @namespace Utils
           * @api public
           */

          module.exports = function objDisplay(obj) {
            var str = inspect(obj),
              type = Object.prototype.toString.call(obj)

            if (
              config.truncateThreshold &&
              str.length >= config.truncateThreshold
            ) {
              if (type === '[object Function]') {
                return !obj.name || obj.name === ''
                  ? '[Function]'
                  : '[Function: ' + obj.name + ']'
              } else if (type === '[object Array]') {
                return '[ Array(' + obj.length + ') ]'
              } else if (type === '[object Object]') {
                var keys = Object.keys(obj),
                  kstr =
                    keys.length > 2
                      ? keys.splice(0, 2).join(', ') + ', ...'
                      : keys.join(', ')
                return '{ Object (' + kstr + ') }'
              } else {
                return str
              }
            } else {
              return str
            }
          }
        },
        { '../config': 4, './inspect': 24 }
      ],
      28: [
        function (require, module, exports) {
          /*!
           * Chai - overwriteChainableMethod utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          var chai = require('../../chai')
          var transferFlags = require('./transferFlags')

          /**
           * ### .overwriteChainableMethod(ctx, name, method, chainingBehavior)
           *
           * Overwrites an already existing chainable method
           * and provides access to the previous function or
           * property.  Must return functions to be used for
           * name.
           *
           *     utils.overwriteChainableMethod(chai.Assertion.prototype, 'lengthOf',
           *       function (_super) {
           *       }
           *     , function (_super) {
           *       }
           *     );
           *
           * Can also be accessed directly from `chai.Assertion`.
           *
           *     chai.Assertion.overwriteChainableMethod('foo', fn, fn);
           *
           * Then can be used as any other assertion.
           *
           *     expect(myFoo).to.have.lengthOf(3);
           *     expect(myFoo).to.have.lengthOf.above(3);
           *
           * @param {Object} ctx object whose method / property is to be overwritten
           * @param {String} name of method / property to overwrite
           * @param {Function} method function that returns a function to be used for name
           * @param {Function} chainingBehavior function that returns a function to be used for property
           * @namespace Utils
           * @name overwriteChainableMethod
           * @api public
           */

          module.exports = function overwriteChainableMethod(
            ctx,
            name,
            method,
            chainingBehavior
          ) {
            var chainableBehavior = ctx.__methods[name]

            var _chainingBehavior = chainableBehavior.chainingBehavior
            chainableBehavior.chainingBehavior =
              function overwritingChainableMethodGetter() {
                var result = chainingBehavior(_chainingBehavior).call(this)
                if (result !== undefined) {
                  return result
                }

                var newAssertion = new chai.Assertion()
                transferFlags(this, newAssertion)
                return newAssertion
              }

            var _method = chainableBehavior.method
            chainableBehavior.method =
              function overwritingChainableMethodWrapper() {
                var result = method(_method).apply(this, arguments)
                if (result !== undefined) {
                  return result
                }

                var newAssertion = new chai.Assertion()
                transferFlags(this, newAssertion)
                return newAssertion
              }
          }
        },
        { '../../chai': 2, './transferFlags': 33 }
      ],
      29: [
        function (require, module, exports) {
          /*!
           * Chai - overwriteMethod utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          var addLengthGuard = require('./addLengthGuard')
          var chai = require('../../chai')
          var flag = require('./flag')
          var proxify = require('./proxify')
          var transferFlags = require('./transferFlags')

          /**
           * ### .overwriteMethod(ctx, name, fn)
           *
           * Overwrites an already existing method and provides
           * access to previous function. Must return function
           * to be used for name.
           *
           *     utils.overwriteMethod(chai.Assertion.prototype, 'equal', function (_super) {
           *       return function (str) {
           *         var obj = utils.flag(this, 'object');
           *         if (obj instanceof Foo) {
           *           new chai.Assertion(obj.value).to.equal(str);
           *         } else {
           *           _super.apply(this, arguments);
           *         }
           *       }
           *     });
           *
           * Can also be accessed directly from `chai.Assertion`.
           *
           *     chai.Assertion.overwriteMethod('foo', fn);
           *
           * Then can be used as any other assertion.
           *
           *     expect(myFoo).to.equal('bar');
           *
           * @param {Object} ctx object whose method is to be overwritten
           * @param {String} name of method to overwrite
           * @param {Function} method function that returns a function to be used for name
           * @namespace Utils
           * @name overwriteMethod
           * @api public
           */

          module.exports = function overwriteMethod(ctx, name, method) {
            var _method = ctx[name],
              _super = function () {
                throw new Error(name + ' is not a function')
              }

            if (_method && 'function' === typeof _method) _super = _method

            var overwritingMethodWrapper = function () {
              // Setting the `ssfi` flag to `overwritingMethodWrapper` causes this
              // function to be the starting point for removing implementation frames from
              // the stack trace of a failed assertion.
              //
              // However, we only want to use this function as the starting point if the
              // `lockSsfi` flag isn't set.
              //
              // If the `lockSsfi` flag is set, then either this assertion has been
              // overwritten by another assertion, or this assertion is being invoked from
              // inside of another assertion. In the first case, the `ssfi` flag has
              // already been set by the overwriting assertion. In the second case, the
              // `ssfi` flag has already been set by the outer assertion.
              if (!flag(this, 'lockSsfi')) {
                flag(this, 'ssfi', overwritingMethodWrapper)
              }

              // Setting the `lockSsfi` flag to `true` prevents the overwritten assertion
              // from changing the `ssfi` flag. By this point, the `ssfi` flag is already
              // set to the correct starting point for this assertion.
              var origLockSsfi = flag(this, 'lockSsfi')
              flag(this, 'lockSsfi', true)
              var result = method(_super).apply(this, arguments)
              flag(this, 'lockSsfi', origLockSsfi)

              if (result !== undefined) {
                return result
              }

              var newAssertion = new chai.Assertion()
              transferFlags(this, newAssertion)
              return newAssertion
            }

            addLengthGuard(overwritingMethodWrapper, name, false)
            ctx[name] = proxify(overwritingMethodWrapper, name)
          }
        },
        {
          '../../chai': 2,
          './addLengthGuard': 10,
          './flag': 15,
          './proxify': 31,
          './transferFlags': 33
        }
      ],
      30: [
        function (require, module, exports) {
          /*!
           * Chai - overwriteProperty utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          var chai = require('../../chai')
          var flag = require('./flag')
          var isProxyEnabled = require('./isProxyEnabled')
          var transferFlags = require('./transferFlags')

          /**
           * ### .overwriteProperty(ctx, name, fn)
           *
           * Overwrites an already existing property getter and provides
           * access to previous value. Must return function to use as getter.
           *
           *     utils.overwriteProperty(chai.Assertion.prototype, 'ok', function (_super) {
           *       return function () {
           *         var obj = utils.flag(this, 'object');
           *         if (obj instanceof Foo) {
           *           new chai.Assertion(obj.name).to.equal('bar');
           *         } else {
           *           _super.call(this);
           *         }
           *       }
           *     });
           *
           *
           * Can also be accessed directly from `chai.Assertion`.
           *
           *     chai.Assertion.overwriteProperty('foo', fn);
           *
           * Then can be used as any other assertion.
           *
           *     expect(myFoo).to.be.ok;
           *
           * @param {Object} ctx object whose property is to be overwritten
           * @param {String} name of property to overwrite
           * @param {Function} getter function that returns a getter function to be used for name
           * @namespace Utils
           * @name overwriteProperty
           * @api public
           */

          module.exports = function overwriteProperty(ctx, name, getter) {
            var _get = Object.getOwnPropertyDescriptor(ctx, name),
              _super = function () {}

            if (_get && 'function' === typeof _get.get) _super = _get.get

            Object.defineProperty(ctx, name, {
              get: function overwritingPropertyGetter() {
                // Setting the `ssfi` flag to `overwritingPropertyGetter` causes this
                // function to be the starting point for removing implementation frames
                // from the stack trace of a failed assertion.
                //
                // However, we only want to use this function as the starting point if
                // the `lockSsfi` flag isn't set and proxy protection is disabled.
                //
                // If the `lockSsfi` flag is set, then either this assertion has been
                // overwritten by another assertion, or this assertion is being invoked
                // from inside of another assertion. In the first case, the `ssfi` flag
                // has already been set by the overwriting assertion. In the second
                // case, the `ssfi` flag has already been set by the outer assertion.
                //
                // If proxy protection is enabled, then the `ssfi` flag has already been
                // set by the proxy getter.
                if (!isProxyEnabled() && !flag(this, 'lockSsfi')) {
                  flag(this, 'ssfi', overwritingPropertyGetter)
                }

                // Setting the `lockSsfi` flag to `true` prevents the overwritten
                // assertion from changing the `ssfi` flag. By this point, the `ssfi`
                // flag is already set to the correct starting point for this assertion.
                var origLockSsfi = flag(this, 'lockSsfi')
                flag(this, 'lockSsfi', true)
                var result = getter(_super).call(this)
                flag(this, 'lockSsfi', origLockSsfi)

                if (result !== undefined) {
                  return result
                }

                var newAssertion = new chai.Assertion()
                transferFlags(this, newAssertion)
                return newAssertion
              },
              configurable: true
            })
          }
        },
        {
          '../../chai': 2,
          './flag': 15,
          './isProxyEnabled': 26,
          './transferFlags': 33
        }
      ],
      31: [
        function (require, module, exports) {
          var config = require('../config')
          var flag = require('./flag')
          var getProperties = require('./getProperties')
          var isProxyEnabled = require('./isProxyEnabled')

          /*!
           * Chai - proxify utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .proxify(object)
           *
           * Return a proxy of given object that throws an error when a non-existent
           * property is read. By default, the root cause is assumed to be a misspelled
           * property, and thus an attempt is made to offer a reasonable suggestion from
           * the list of existing properties. However, if a nonChainableMethodName is
           * provided, then the root cause is instead a failure to invoke a non-chainable
           * method prior to reading the non-existent property.
           *
           * If proxies are unsupported or disabled via the user's Chai config, then
           * return object without modification.
           *
           * @param {Object} obj
           * @param {String} nonChainableMethodName
           * @namespace Utils
           * @name proxify
           */

          var builtins = ['__flags', '__methods', '_obj', 'assert']

          module.exports = function proxify(obj, nonChainableMethodName) {
            if (!isProxyEnabled()) return obj

            return new Proxy(obj, {
              get: function proxyGetter(target, property) {
                // This check is here because we should not throw errors on Symbol properties
                // such as `Symbol.toStringTag`.
                // The values for which an error should be thrown can be configured using
                // the `config.proxyExcludedKeys` setting.
                if (
                  typeof property === 'string' &&
                  config.proxyExcludedKeys.indexOf(property) === -1 &&
                  !Reflect.has(target, property)
                ) {
                  // Special message for invalid property access of non-chainable methods.
                  if (nonChainableMethodName) {
                    throw Error(
                      'Invalid Chai property: ' +
                        nonChainableMethodName +
                        '.' +
                        property +
                        '. See docs for proper usage of "' +
                        nonChainableMethodName +
                        '".'
                    )
                  }

                  // If the property is reasonably close to an existing Chai property,
                  // suggest that property to the user. Only suggest properties with a
                  // distance less than 4.
                  var suggestion = null
                  var suggestionDistance = 4
                  getProperties(target).forEach(function (prop) {
                    if (
                      !Object.prototype.hasOwnProperty(prop) &&
                      builtins.indexOf(prop) === -1
                    ) {
                      var dist = stringDistanceCapped(
                        property,
                        prop,
                        suggestionDistance
                      )
                      if (dist < suggestionDistance) {
                        suggestion = prop
                        suggestionDistance = dist
                      }
                    }
                  })

                  if (suggestion !== null) {
                    throw Error(
                      'Invalid Chai property: ' +
                        property +
                        '. Did you mean "' +
                        suggestion +
                        '"?'
                    )
                  } else {
                    throw Error('Invalid Chai property: ' + property)
                  }
                }

                // Use this proxy getter as the starting point for removing implementation
                // frames from the stack trace of a failed assertion. For property
                // assertions, this prevents the proxy getter from showing up in the stack
                // trace since it's invoked before the property getter. For method and
                // chainable method assertions, this flag will end up getting changed to
                // the method wrapper, which is good since this frame will no longer be in
                // the stack once the method is invoked. Note that Chai builtin assertion
                // properties such as `__flags` are skipped since this is only meant to
                // capture the starting point of an assertion. This step is also skipped
                // if the `lockSsfi` flag is set, thus indicating that this assertion is
                // being called from within another assertion. In that case, the `ssfi`
                // flag is already set to the outer assertion's starting point.
                if (
                  builtins.indexOf(property) === -1 &&
                  !flag(target, 'lockSsfi')
                ) {
                  flag(target, 'ssfi', proxyGetter)
                }

                return Reflect.get(target, property)
              }
            })
          }

          /**
           * # stringDistanceCapped(strA, strB, cap)
           * Return the Levenshtein distance between two strings, but no more than cap.
           * @param {string} strA
           * @param {string} strB
           * @param {number} number
           * @return {number} min(string distance between strA and strB, cap)
           * @api private
           */

          function stringDistanceCapped(strA, strB, cap) {
            if (Math.abs(strA.length - strB.length) >= cap) {
              return cap
            }

            var memo = []
            // `memo` is a two-dimensional array containing distances.
            // memo[i][j] is the distance between strA.slice(0, i) and
            // strB.slice(0, j).
            for (var i = 0; i <= strA.length; i++) {
              memo[i] = Array(strB.length + 1).fill(0)
              memo[i][0] = i
            }
            for (var j = 0; j < strB.length; j++) {
              memo[0][j] = j
            }

            for (var i = 1; i <= strA.length; i++) {
              var ch = strA.charCodeAt(i - 1)
              for (var j = 1; j <= strB.length; j++) {
                if (Math.abs(i - j) >= cap) {
                  memo[i][j] = cap
                  continue
                }
                memo[i][j] = Math.min(
                  memo[i - 1][j] + 1,
                  memo[i][j - 1] + 1,
                  memo[i - 1][j - 1] + (ch === strB.charCodeAt(j - 1) ? 0 : 1)
                )
              }
            }

            return memo[strA.length][strB.length]
          }
        },
        {
          '../config': 4,
          './flag': 15,
          './getProperties': 22,
          './isProxyEnabled': 26
        }
      ],
      32: [
        function (require, module, exports) {
          /*!
           * Chai - test utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /*!
           * Module dependencies
           */

          var flag = require('./flag')

          /**
           * ### .test(object, expression)
           *
           * Test and object for expression.
           *
           * @param {Object} object (constructed Assertion)
           * @param {Arguments} chai.Assertion.prototype.assert arguments
           * @namespace Utils
           * @name test
           */

          module.exports = function test(obj, args) {
            var negate = flag(obj, 'negate'),
              expr = args[0]
            return negate ? !expr : expr
          }
        },
        { './flag': 15 }
      ],
      33: [
        function (require, module, exports) {
          /*!
           * Chai - transferFlags utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .transferFlags(assertion, object, includeAll = true)
           *
           * Transfer all the flags for `assertion` to `object`. If
           * `includeAll` is set to `false`, then the base Chai
           * assertion flags (namely `object`, `ssfi`, `lockSsfi`,
           * and `message`) will not be transferred.
           *
           *
           *     var newAssertion = new Assertion();
           *     utils.transferFlags(assertion, newAssertion);
           *
           *     var anotherAssertion = new Assertion(myObj);
           *     utils.transferFlags(assertion, anotherAssertion, false);
           *
           * @param {Assertion} assertion the assertion to transfer the flags from
           * @param {Object} object the object to transfer the flags to; usually a new assertion
           * @param {Boolean} includeAll
           * @namespace Utils
           * @name transferFlags
           * @api private
           */

          module.exports = function transferFlags(
            assertion,
            object,
            includeAll
          ) {
            var flags =
              assertion.__flags || (assertion.__flags = Object.create(null))

            if (!object.__flags) {
              object.__flags = Object.create(null)
            }

            includeAll = arguments.length === 3 ? includeAll : true

            for (var flag in flags) {
              if (
                includeAll ||
                (flag !== 'object' &&
                  flag !== 'ssfi' &&
                  flag !== 'lockSsfi' &&
                  flag != 'message')
              ) {
                object.__flags[flag] = flags[flag]
              }
            }
          }
        },
        {}
      ],
      34: [
        function (require, module, exports) {
          /*!
           * assertion-error
           * Copyright(c) 2013 Jake Luer <jake@qualiancy.com>
           * MIT Licensed
           */

          /*!
           * Return a function that will copy properties from
           * one object to another excluding any originally
           * listed. Returned function will create a new `{}`.
           *
           * @param {String} excluded properties ...
           * @return {Function}
           */

          function exclude() {
            var excludes = [].slice.call(arguments)

            function excludeProps(res, obj) {
              Object.keys(obj).forEach(function (key) {
                if (!~excludes.indexOf(key)) res[key] = obj[key]
              })
            }

            return function extendExclude() {
              var args = [].slice.call(arguments),
                i = 0,
                res = {}

              for (; i < args.length; i++) {
                excludeProps(res, args[i])
              }

              return res
            }
          }

          /*!
           * Primary Exports
           */

          module.exports = AssertionError

          /**
           * ### AssertionError
           *
           * An extension of the JavaScript `Error` constructor for
           * assertion and validation scenarios.
           *
           * @param {String} message
           * @param {Object} properties to include (optional)
           * @param {callee} start stack function (optional)
           */

          function AssertionError(message, _props, ssf) {
            var extend = exclude(
                'name',
                'message',
                'stack',
                'constructor',
                'toJSON'
              ),
              props = extend(_props || {})

            // default values
            this.message = message || 'Unspecified AssertionError'
            this.showDiff = false

            // copy from properties
            for (var key in props) {
              this[key] = props[key]
            }

            // capture stack trace
            ssf = ssf || AssertionError
            if (Error.captureStackTrace) {
              Error.captureStackTrace(this, ssf)
            } else {
              try {
                throw new Error()
              } catch (e) {
                this.stack = e.stack
              }
            }
          }

          /*!
           * Inherit from Error.prototype
           */

          AssertionError.prototype = Object.create(Error.prototype)

          /*!
           * Statically set name
           */

          AssertionError.prototype.name = 'AssertionError'

          /*!
           * Ensure correct constructor
           */

          AssertionError.prototype.constructor = AssertionError

          /**
           * Allow errors to be converted to JSON for static transfer.
           *
           * @param {Boolean} include stack (default: `true`)
           * @return {Object} object that can be `JSON.stringify`
           */

          AssertionError.prototype.toJSON = function (stack) {
            var extend = exclude('constructor', 'toJSON', 'stack'),
              props = extend({ name: this.name }, this)

            // include stack if exists and not turned off
            if (false !== stack && this.stack) {
              props.stack = this.stack
            }

            return props
          }
        },
        {}
      ],
      35: [
        function (require, module, exports) {
          'use strict'

          /* !
           * Chai - checkError utility
           * Copyright(c) 2012-2016 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .checkError
           *
           * Checks that an error conforms to a given set of criteria and/or retrieves information about it.
           *
           * @api public
           */

          /**
           * ### .compatibleInstance(thrown, errorLike)
           *
           * Checks if two instances are compatible (strict equal).
           * Returns false if errorLike is not an instance of Error, because instances
           * can only be compatible if they're both error instances.
           *
           * @name compatibleInstance
           * @param {Error} thrown error
           * @param {Error|ErrorConstructor} errorLike object to compare against
           * @namespace Utils
           * @api public
           */

          function compatibleInstance(thrown, errorLike) {
            return errorLike instanceof Error && thrown === errorLike
          }

          /**
           * ### .compatibleConstructor(thrown, errorLike)
           *
           * Checks if two constructors are compatible.
           * This function can receive either an error constructor or
           * an error instance as the `errorLike` argument.
           * Constructors are compatible if they're the same or if one is
           * an instance of another.
           *
           * @name compatibleConstructor
           * @param {Error} thrown error
           * @param {Error|ErrorConstructor} errorLike object to compare against
           * @namespace Utils
           * @api public
           */

          function compatibleConstructor(thrown, errorLike) {
            if (errorLike instanceof Error) {
              // If `errorLike` is an instance of any error we compare their constructors
              return (
                thrown.constructor === errorLike.constructor ||
                thrown instanceof errorLike.constructor
              )
            } else if (
              errorLike.prototype instanceof Error ||
              errorLike === Error
            ) {
              // If `errorLike` is a constructor that inherits from Error, we compare `thrown` to `errorLike` directly
              return (
                thrown.constructor === errorLike || thrown instanceof errorLike
              )
            }

            return false
          }

          /**
           * ### .compatibleMessage(thrown, errMatcher)
           *
           * Checks if an error's message is compatible with a matcher (String or RegExp).
           * If the message contains the String or passes the RegExp test,
           * it is considered compatible.
           *
           * @name compatibleMessage
           * @param {Error} thrown error
           * @param {String|RegExp} errMatcher to look for into the message
           * @namespace Utils
           * @api public
           */

          function compatibleMessage(thrown, errMatcher) {
            var comparisonString =
              typeof thrown === 'string' ? thrown : thrown.message
            if (errMatcher instanceof RegExp) {
              return errMatcher.test(comparisonString)
            } else if (typeof errMatcher === 'string') {
              return comparisonString.indexOf(errMatcher) !== -1 // eslint-disable-line no-magic-numbers
            }

            return false
          }

          /**
           * ### .getFunctionName(constructorFn)
           *
           * Returns the name of a function.
           * This also includes a polyfill function if `constructorFn.name` is not defined.
           *
           * @name getFunctionName
           * @param {Function} constructorFn
           * @namespace Utils
           * @api private
           */

          var functionNameMatch =
            /\s*function(?:\s|\s*\/\*[^(?:*\/)]+\*\/\s*)*([^\(\/]+)/
          function getFunctionName(constructorFn) {
            var name = ''
            if (typeof constructorFn.name === 'undefined') {
              // Here we run a polyfill if constructorFn.name is not defined
              var match = String(constructorFn).match(functionNameMatch)
              if (match) {
                name = match[1]
              }
            } else {
              name = constructorFn.name
            }

            return name
          }

          /**
           * ### .getConstructorName(errorLike)
           *
           * Gets the constructor name for an Error instance or constructor itself.
           *
           * @name getConstructorName
           * @param {Error|ErrorConstructor} errorLike
           * @namespace Utils
           * @api public
           */

          function getConstructorName(errorLike) {
            var constructorName = errorLike
            if (errorLike instanceof Error) {
              constructorName = getFunctionName(errorLike.constructor)
            } else if (typeof errorLike === 'function') {
              // If `err` is not an instance of Error it is an error constructor itself or another function.
              // If we've got a common function we get its name, otherwise we may need to create a new instance
              // of the error just in case it's a poorly-constructed error. Please see chaijs/chai/issues/45 to know more.
              constructorName =
                getFunctionName(errorLike).trim() ||
                getFunctionName(new errorLike()) // eslint-disable-line new-cap
            }

            return constructorName
          }

          /**
           * ### .getMessage(errorLike)
           *
           * Gets the error message from an error.
           * If `err` is a String itself, we return it.
           * If the error has no message, we return an empty string.
           *
           * @name getMessage
           * @param {Error|String} errorLike
           * @namespace Utils
           * @api public
           */

          function getMessage(errorLike) {
            var msg = ''
            if (errorLike && errorLike.message) {
              msg = errorLike.message
            } else if (typeof errorLike === 'string') {
              msg = errorLike
            }

            return msg
          }

          module.exports = {
            compatibleInstance: compatibleInstance,
            compatibleConstructor: compatibleConstructor,
            compatibleMessage: compatibleMessage,
            getMessage: getMessage,
            getConstructorName: getConstructorName
          }
        },
        {}
      ],
      36: [
        function (require, module, exports) {
          'use strict'
          /* globals Symbol: false, Uint8Array: false, WeakMap: false */
          /*!
           * deep-eql
           * Copyright(c) 2013 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          var type = require('type-detect')
          function FakeMap() {
            this._key = 'chai/deep-eql__' + Math.random() + Date.now()
          }

          FakeMap.prototype = {
            get: function getMap(key) {
              return key[this._key]
            },
            set: function setMap(key, value) {
              if (Object.isExtensible(key)) {
                Object.defineProperty(key, this._key, {
                  value: value,
                  configurable: true
                })
              }
            }
          }

          var MemoizeMap = typeof WeakMap === 'function' ? WeakMap : FakeMap
          /*!
           * Check to see if the MemoizeMap has recorded a result of the two operands
           *
           * @param {Mixed} leftHandOperand
           * @param {Mixed} rightHandOperand
           * @param {MemoizeMap} memoizeMap
           * @returns {Boolean|null} result
           */
          function memoizeCompare(
            leftHandOperand,
            rightHandOperand,
            memoizeMap
          ) {
            // Technically, WeakMap keys can *only* be objects, not primitives.
            if (
              !memoizeMap ||
              isPrimitive(leftHandOperand) ||
              isPrimitive(rightHandOperand)
            ) {
              return null
            }
            var leftHandMap = memoizeMap.get(leftHandOperand)
            if (leftHandMap) {
              var result = leftHandMap.get(rightHandOperand)
              if (typeof result === 'boolean') {
                return result
              }
            }
            return null
          }

          /*!
           * Set the result of the equality into the MemoizeMap
           *
           * @param {Mixed} leftHandOperand
           * @param {Mixed} rightHandOperand
           * @param {MemoizeMap} memoizeMap
           * @param {Boolean} result
           */
          function memoizeSet(
            leftHandOperand,
            rightHandOperand,
            memoizeMap,
            result
          ) {
            // Technically, WeakMap keys can *only* be objects, not primitives.
            if (
              !memoizeMap ||
              isPrimitive(leftHandOperand) ||
              isPrimitive(rightHandOperand)
            ) {
              return
            }
            var leftHandMap = memoizeMap.get(leftHandOperand)
            if (leftHandMap) {
              leftHandMap.set(rightHandOperand, result)
            } else {
              leftHandMap = new MemoizeMap()
              leftHandMap.set(rightHandOperand, result)
              memoizeMap.set(leftHandOperand, leftHandMap)
            }
          }

          /*!
           * Primary Export
           */

          module.exports = deepEqual
          module.exports.MemoizeMap = MemoizeMap

          /**
 * Assert deeply nested sameValue equality between two objects of any type.
 *
 * @param {Mixed} leftHandOperand
 * @param {Mixed} rightHandOperand
 * @param {Object} [options] (optional) Additional options
 * @param {Array} [options.comparator] (optional) Override default algorithm, determining custom equality.
 * @param {Array} [options.memoize] (optional) Provide a custom memoization object which will cache the results of
    complex objects for a speed boost. By passing `false` you can disable memoization, but this will cause circular
    references to blow the stack.
 * @return {Boolean} equal match
 */
          function deepEqual(leftHandOperand, rightHandOperand, options) {
            // If we have a comparator, we can't assume anything; so bail to its check first.
            if (options && options.comparator) {
              return extensiveDeepEqual(
                leftHandOperand,
                rightHandOperand,
                options
              )
            }

            var simpleResult = simpleEqual(leftHandOperand, rightHandOperand)
            if (simpleResult !== null) {
              return simpleResult
            }

            // Deeper comparisons are pushed through to a larger function
            return extensiveDeepEqual(
              leftHandOperand,
              rightHandOperand,
              options
            )
          }

          /**
           * Many comparisons can be canceled out early via simple equality or primitive checks.
           * @param {Mixed} leftHandOperand
           * @param {Mixed} rightHandOperand
           * @return {Boolean|null} equal match
           */
          function simpleEqual(leftHandOperand, rightHandOperand) {
            // Equal references (except for Numbers) can be returned early
            if (leftHandOperand === rightHandOperand) {
              // Handle +-0 cases
              return (
                leftHandOperand !== 0 ||
                1 / leftHandOperand === 1 / rightHandOperand
              )
            }

            // handle NaN cases
            if (
              leftHandOperand !== leftHandOperand && // eslint-disable-line no-self-compare
              rightHandOperand !== rightHandOperand // eslint-disable-line no-self-compare
            ) {
              return true
            }

            // Anything that is not an 'object', i.e. symbols, functions, booleans, numbers,
            // strings, and undefined, can be compared by reference.
            if (isPrimitive(leftHandOperand) || isPrimitive(rightHandOperand)) {
              // Easy out b/c it would have passed the first equality check
              return false
            }
            return null
          }

          /*!
 * The main logic of the `deepEqual` function.
 *
 * @param {Mixed} leftHandOperand
 * @param {Mixed} rightHandOperand
 * @param {Object} [options] (optional) Additional options
 * @param {Array} [options.comparator] (optional) Override default algorithm, determining custom equality.
 * @param {Array} [options.memoize] (optional) Provide a custom memoization object which will cache the results of
    complex objects for a speed boost. By passing `false` you can disable memoization, but this will cause circular
    references to blow the stack.
 * @return {Boolean} equal match
*/
          function extensiveDeepEqual(
            leftHandOperand,
            rightHandOperand,
            options
          ) {
            options = options || {}
            options.memoize =
              options.memoize === false
                ? false
                : options.memoize || new MemoizeMap()
            var comparator = options && options.comparator

            // Check if a memoized result exists.
            var memoizeResultLeft = memoizeCompare(
              leftHandOperand,
              rightHandOperand,
              options.memoize
            )
            if (memoizeResultLeft !== null) {
              return memoizeResultLeft
            }
            var memoizeResultRight = memoizeCompare(
              rightHandOperand,
              leftHandOperand,
              options.memoize
            )
            if (memoizeResultRight !== null) {
              return memoizeResultRight
            }

            // If a comparator is present, use it.
            if (comparator) {
              var comparatorResult = comparator(
                leftHandOperand,
                rightHandOperand
              )
              // Comparators may return null, in which case we want to go back to default behavior.
              if (comparatorResult === false || comparatorResult === true) {
                memoizeSet(
                  leftHandOperand,
                  rightHandOperand,
                  options.memoize,
                  comparatorResult
                )
                return comparatorResult
              }
              // To allow comparators to override *any* behavior, we ran them first. Since it didn't decide
              // what to do, we need to make sure to return the basic tests first before we move on.
              var simpleResult = simpleEqual(leftHandOperand, rightHandOperand)
              if (simpleResult !== null) {
                // Don't memoize this, it takes longer to set/retrieve than to just compare.
                return simpleResult
              }
            }

            var leftHandType = type(leftHandOperand)
            if (leftHandType !== type(rightHandOperand)) {
              memoizeSet(
                leftHandOperand,
                rightHandOperand,
                options.memoize,
                false
              )
              return false
            }

            // Temporarily set the operands in the memoize object to prevent blowing the stack
            memoizeSet(leftHandOperand, rightHandOperand, options.memoize, true)

            var result = extensiveDeepEqualByType(
              leftHandOperand,
              rightHandOperand,
              leftHandType,
              options
            )
            memoizeSet(
              leftHandOperand,
              rightHandOperand,
              options.memoize,
              result
            )
            return result
          }

          function extensiveDeepEqualByType(
            leftHandOperand,
            rightHandOperand,
            leftHandType,
            options
          ) {
            switch (leftHandType) {
              case 'String':
              case 'Number':
              case 'Boolean':
              case 'Date':
                // If these types are their instance types (e.g. `new Number`) then re-deepEqual against their values
                return deepEqual(
                  leftHandOperand.valueOf(),
                  rightHandOperand.valueOf()
                )
              case 'Promise':
              case 'Symbol':
              case 'function':
              case 'WeakMap':
              case 'WeakSet':
              case 'Error':
                return leftHandOperand === rightHandOperand
              case 'Arguments':
              case 'Int8Array':
              case 'Uint8Array':
              case 'Uint8ClampedArray':
              case 'Int16Array':
              case 'Uint16Array':
              case 'Int32Array':
              case 'Uint32Array':
              case 'Float32Array':
              case 'Float64Array':
              case 'Array':
                return iterableEqual(leftHandOperand, rightHandOperand, options)
              case 'RegExp':
                return regexpEqual(leftHandOperand, rightHandOperand)
              case 'Generator':
                return generatorEqual(
                  leftHandOperand,
                  rightHandOperand,
                  options
                )
              case 'DataView':
                return iterableEqual(
                  new Uint8Array(leftHandOperand.buffer),
                  new Uint8Array(rightHandOperand.buffer),
                  options
                )
              case 'ArrayBuffer':
                return iterableEqual(
                  new Uint8Array(leftHandOperand),
                  new Uint8Array(rightHandOperand),
                  options
                )
              case 'Set':
                return entriesEqual(leftHandOperand, rightHandOperand, options)
              case 'Map':
                return entriesEqual(leftHandOperand, rightHandOperand, options)
              default:
                return objectEqual(leftHandOperand, rightHandOperand, options)
            }
          }

          /*!
           * Compare two Regular Expressions for equality.
           *
           * @param {RegExp} leftHandOperand
           * @param {RegExp} rightHandOperand
           * @return {Boolean} result
           */

          function regexpEqual(leftHandOperand, rightHandOperand) {
            return leftHandOperand.toString() === rightHandOperand.toString()
          }

          /*!
           * Compare two Sets/Maps for equality. Faster than other equality functions.
           *
           * @param {Set} leftHandOperand
           * @param {Set} rightHandOperand
           * @param {Object} [options] (Optional)
           * @return {Boolean} result
           */

          function entriesEqual(leftHandOperand, rightHandOperand, options) {
            // IE11 doesn't support Set#entries or Set#@@iterator, so we need manually populate using Set#forEach
            if (leftHandOperand.size !== rightHandOperand.size) {
              return false
            }
            if (leftHandOperand.size === 0) {
              return true
            }
            var leftHandItems = []
            var rightHandItems = []
            leftHandOperand.forEach(function gatherEntries(key, value) {
              leftHandItems.push([key, value])
            })
            rightHandOperand.forEach(function gatherEntries(key, value) {
              rightHandItems.push([key, value])
            })
            return iterableEqual(
              leftHandItems.sort(),
              rightHandItems.sort(),
              options
            )
          }

          /*!
           * Simple equality for flat iterable objects such as Arrays, TypedArrays or Node.js buffers.
           *
           * @param {Iterable} leftHandOperand
           * @param {Iterable} rightHandOperand
           * @param {Object} [options] (Optional)
           * @return {Boolean} result
           */

          function iterableEqual(leftHandOperand, rightHandOperand, options) {
            var length = leftHandOperand.length
            if (length !== rightHandOperand.length) {
              return false
            }
            if (length === 0) {
              return true
            }
            var index = -1
            while (++index < length) {
              if (
                deepEqual(
                  leftHandOperand[index],
                  rightHandOperand[index],
                  options
                ) === false
              ) {
                return false
              }
            }
            return true
          }

          /*!
           * Simple equality for generator objects such as those returned by generator functions.
           *
           * @param {Iterable} leftHandOperand
           * @param {Iterable} rightHandOperand
           * @param {Object} [options] (Optional)
           * @return {Boolean} result
           */

          function generatorEqual(leftHandOperand, rightHandOperand, options) {
            return iterableEqual(
              getGeneratorEntries(leftHandOperand),
              getGeneratorEntries(rightHandOperand),
              options
            )
          }

          /*!
           * Determine if the given object has an @@iterator function.
           *
           * @param {Object} target
           * @return {Boolean} `true` if the object has an @@iterator function.
           */
          function hasIteratorFunction(target) {
            return (
              typeof Symbol !== 'undefined' &&
              typeof target === 'object' &&
              typeof Symbol.iterator !== 'undefined' &&
              typeof target[Symbol.iterator] === 'function'
            )
          }

          /*!
           * Gets all iterator entries from the given Object. If the Object has no @@iterator function, returns an empty array.
           * This will consume the iterator - which could have side effects depending on the @@iterator implementation.
           *
           * @param {Object} target
           * @returns {Array} an array of entries from the @@iterator function
           */
          function getIteratorEntries(target) {
            if (hasIteratorFunction(target)) {
              try {
                return getGeneratorEntries(target[Symbol.iterator]())
              } catch (iteratorError) {
                return []
              }
            }
            return []
          }

          /*!
           * Gets all entries from a Generator. This will consume the generator - which could have side effects.
           *
           * @param {Generator} target
           * @returns {Array} an array of entries from the Generator.
           */
          function getGeneratorEntries(generator) {
            var generatorResult = generator.next()
            var accumulator = [generatorResult.value]
            while (generatorResult.done === false) {
              generatorResult = generator.next()
              accumulator.push(generatorResult.value)
            }
            return accumulator
          }

          /*!
           * Gets all own and inherited enumerable keys from a target.
           *
           * @param {Object} target
           * @returns {Array} an array of own and inherited enumerable keys from the target.
           */
          function getEnumerableKeys(target) {
            var keys = []
            for (var key in target) {
              keys.push(key)
            }
            return keys
          }

          /*!
           * Determines if two objects have matching values, given a set of keys. Defers to deepEqual for the equality check of
           * each key. If any value of the given key is not equal, the function will return false (early).
           *
           * @param {Mixed} leftHandOperand
           * @param {Mixed} rightHandOperand
           * @param {Array} keys An array of keys to compare the values of leftHandOperand and rightHandOperand against
           * @param {Object} [options] (Optional)
           * @return {Boolean} result
           */
          function keysEqual(leftHandOperand, rightHandOperand, keys, options) {
            var length = keys.length
            if (length === 0) {
              return true
            }
            for (var i = 0; i < length; i += 1) {
              if (
                deepEqual(
                  leftHandOperand[keys[i]],
                  rightHandOperand[keys[i]],
                  options
                ) === false
              ) {
                return false
              }
            }
            return true
          }

          /*!
           * Recursively check the equality of two Objects. Once basic sameness has been established it will defer to `deepEqual`
           * for each enumerable key in the object.
           *
           * @param {Mixed} leftHandOperand
           * @param {Mixed} rightHandOperand
           * @param {Object} [options] (Optional)
           * @return {Boolean} result
           */

          function objectEqual(leftHandOperand, rightHandOperand, options) {
            var leftHandKeys = getEnumerableKeys(leftHandOperand)
            var rightHandKeys = getEnumerableKeys(rightHandOperand)
            if (
              leftHandKeys.length &&
              leftHandKeys.length === rightHandKeys.length
            ) {
              leftHandKeys.sort()
              rightHandKeys.sort()
              if (iterableEqual(leftHandKeys, rightHandKeys) === false) {
                return false
              }
              return keysEqual(
                leftHandOperand,
                rightHandOperand,
                leftHandKeys,
                options
              )
            }

            var leftHandEntries = getIteratorEntries(leftHandOperand)
            var rightHandEntries = getIteratorEntries(rightHandOperand)
            if (
              leftHandEntries.length &&
              leftHandEntries.length === rightHandEntries.length
            ) {
              leftHandEntries.sort()
              rightHandEntries.sort()
              return iterableEqual(leftHandEntries, rightHandEntries, options)
            }

            if (
              leftHandKeys.length === 0 &&
              leftHandEntries.length === 0 &&
              rightHandKeys.length === 0 &&
              rightHandEntries.length === 0
            ) {
              return true
            }

            return false
          }

          /*!
           * Returns true if the argument is a primitive.
           *
           * This intentionally returns true for all objects that can be compared by reference,
           * including functions and symbols.
           *
           * @param {Mixed} value
           * @return {Boolean} result
           */
          function isPrimitive(value) {
            return value === null || typeof value !== 'object'
          }
        },
        { 'type-detect': 39 }
      ],
      37: [
        function (require, module, exports) {
          'use strict'

          /* !
           * Chai - getFuncName utility
           * Copyright(c) 2012-2016 Jake Luer <jake@alogicalparadox.com>
           * MIT Licensed
           */

          /**
           * ### .getFuncName(constructorFn)
           *
           * Returns the name of a function.
           * When a non-function instance is passed, returns `null`.
           * This also includes a polyfill function if `aFunc.name` is not defined.
           *
           * @name getFuncName
           * @param {Function} funct
           * @namespace Utils
           * @api public
           */

          var toString = Function.prototype.toString
          var functionNameMatch =
            /\s*function(?:\s|\s*\/\*[^(?:*\/)]+\*\/\s*)*([^\s\(\/]+)/
          function getFuncName(aFunc) {
            if (typeof aFunc !== 'function') {
              return null
            }

            var name = ''
            if (
              typeof Function.prototype.name === 'undefined' &&
              typeof aFunc.name === 'undefined'
            ) {
              // Here we run a polyfill if Function does not support the `name` property and if aFunc.name is not defined
              var match = toString.call(aFunc).match(functionNameMatch)
              if (match) {
                name = match[1]
              }
            } else {
              // If we've got a `name` property we just use it
              name = aFunc.name
            }

            return name
          }

          module.exports = getFuncName
        },
        {}
      ],
      38: [
        function (require, module, exports) {
          'use strict'

          /* !
           * Chai - pathval utility
           * Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
           * @see https://github.com/logicalparadox/filtr
           * MIT Licensed
           */

          /**
           * ### .hasProperty(object, name)
           *
           * This allows checking whether an object has own
           * or inherited from prototype chain named property.
           *
           * Basically does the same thing as the `in`
           * operator but works properly with null/undefined values
           * and other primitives.
           *
           *     var obj = {
           *         arr: ['a', 'b', 'c']
           *       , str: 'Hello'
           *     }
           *
           * The following would be the results.
           *
           *     hasProperty(obj, 'str');  // true
           *     hasProperty(obj, 'constructor');  // true
           *     hasProperty(obj, 'bar');  // false
           *
           *     hasProperty(obj.str, 'length'); // true
           *     hasProperty(obj.str, 1);  // true
           *     hasProperty(obj.str, 5);  // false
           *
           *     hasProperty(obj.arr, 'length');  // true
           *     hasProperty(obj.arr, 2);  // true
           *     hasProperty(obj.arr, 3);  // false
           *
           * @param {Object} object
           * @param {String|Symbol} name
           * @returns {Boolean} whether it exists
           * @namespace Utils
           * @name hasProperty
           * @api public
           */

          function hasProperty(obj, name) {
            if (typeof obj === 'undefined' || obj === null) {
              return false
            }

            // The `in` operator does not work with primitives.
            return name in Object(obj)
          }

          /* !
           * ## parsePath(path)
           *
           * Helper function used to parse string object
           * paths. Use in conjunction with `internalGetPathValue`.
           *
           *      var parsed = parsePath('myobject.property.subprop');
           *
           * ### Paths:
           *
           * * Can be infinitely deep and nested.
           * * Arrays are also valid using the formal `myobject.document[3].property`.
           * * Literal dots and brackets (not delimiter) must be backslash-escaped.
           *
           * @param {String} path
           * @returns {Object} parsed
           * @api private
           */

          function parsePath(path) {
            var str = path.replace(/([^\\])\[/g, '$1.[')
            var parts = str.match(/(\\\.|[^.]+?)+/g)
            return parts.map(function mapMatches(value) {
              if (
                value === 'constructor' ||
                value === '__proto__' ||
                value === 'prototype'
              ) {
                return {}
              }
              var regexp = /^\[(\d+)\]$/
              var mArr = regexp.exec(value)
              var parsed = null
              if (mArr) {
                parsed = { i: parseFloat(mArr[1]) }
              } else {
                parsed = { p: value.replace(/\\([.[\]])/g, '$1') }
              }

              return parsed
            })
          }

          /* !
           * ## internalGetPathValue(obj, parsed[, pathDepth])
           *
           * Helper companion function for `.parsePath` that returns
           * the value located at the parsed address.
           *
           *      var value = getPathValue(obj, parsed);
           *
           * @param {Object} object to search against
           * @param {Object} parsed definition from `parsePath`.
           * @param {Number} depth (nesting level) of the property we want to retrieve
           * @returns {Object|Undefined} value
           * @api private
           */

          function internalGetPathValue(obj, parsed, pathDepth) {
            var temporaryValue = obj
            var res = null
            pathDepth =
              typeof pathDepth === 'undefined' ? parsed.length : pathDepth

            for (var i = 0; i < pathDepth; i++) {
              var part = parsed[i]
              if (temporaryValue) {
                if (typeof part.p === 'undefined') {
                  temporaryValue = temporaryValue[part.i]
                } else {
                  temporaryValue = temporaryValue[part.p]
                }

                if (i === pathDepth - 1) {
                  res = temporaryValue
                }
              }
            }

            return res
          }

          /* !
           * ## internalSetPathValue(obj, value, parsed)
           *
           * Companion function for `parsePath` that sets
           * the value located at a parsed address.
           *
           *  internalSetPathValue(obj, 'value', parsed);
           *
           * @param {Object} object to search and define on
           * @param {*} value to use upon set
           * @param {Object} parsed definition from `parsePath`
           * @api private
           */

          function internalSetPathValue(obj, val, parsed) {
            var tempObj = obj
            var pathDepth = parsed.length
            var part = null
            // Here we iterate through every part of the path
            for (var i = 0; i < pathDepth; i++) {
              var propName = null
              var propVal = null
              part = parsed[i]

              // If it's the last part of the path, we set the 'propName' value with the property name
              if (i === pathDepth - 1) {
                propName = typeof part.p === 'undefined' ? part.i : part.p
                // Now we set the property with the name held by 'propName' on object with the desired val
                tempObj[propName] = val
              } else if (typeof part.p !== 'undefined' && tempObj[part.p]) {
                tempObj = tempObj[part.p]
              } else if (typeof part.i !== 'undefined' && tempObj[part.i]) {
                tempObj = tempObj[part.i]
              } else {
                // If the obj doesn't have the property we create one with that name to define it
                var next = parsed[i + 1]
                // Here we set the name of the property which will be defined
                propName = typeof part.p === 'undefined' ? part.i : part.p
                // Here we decide if this property will be an array or a new object
                propVal = typeof next.p === 'undefined' ? [] : {}
                tempObj[propName] = propVal
                tempObj = tempObj[propName]
              }
            }
          }

          /**
           * ### .getPathInfo(object, path)
           *
           * This allows the retrieval of property info in an
           * object given a string path.
           *
           * The path info consists of an object with the
           * following properties:
           *
           * * parent - The parent object of the property referenced by `path`
           * * name - The name of the final property, a number if it was an array indexer
           * * value - The value of the property, if it exists, otherwise `undefined`
           * * exists - Whether the property exists or not
           *
           * @param {Object} object
           * @param {String} path
           * @returns {Object} info
           * @namespace Utils
           * @name getPathInfo
           * @api public
           */

          function getPathInfo(obj, path) {
            var parsed = parsePath(path)
            var last = parsed[parsed.length - 1]
            var info = {
              parent:
                parsed.length > 1
                  ? internalGetPathValue(obj, parsed, parsed.length - 1)
                  : obj,
              name: last.p || last.i,
              value: internalGetPathValue(obj, parsed)
            }
            info.exists = hasProperty(info.parent, info.name)

            return info
          }

          /**
           * ### .getPathValue(object, path)
           *
           * This allows the retrieval of values in an
           * object given a string path.
           *
           *     var obj = {
           *         prop1: {
           *             arr: ['a', 'b', 'c']
           *           , str: 'Hello'
           *         }
           *       , prop2: {
           *             arr: [ { nested: 'Universe' } ]
           *           , str: 'Hello again!'
           *         }
           *     }
           *
           * The following would be the results.
           *
           *     getPathValue(obj, 'prop1.str'); // Hello
           *     getPathValue(obj, 'prop1.att[2]'); // b
           *     getPathValue(obj, 'prop2.arr[0].nested'); // Universe
           *
           * @param {Object} object
           * @param {String} path
           * @returns {Object} value or `undefined`
           * @namespace Utils
           * @name getPathValue
           * @api public
           */

          function getPathValue(obj, path) {
            var info = getPathInfo(obj, path)
            return info.value
          }

          /**
           * ### .setPathValue(object, path, value)
           *
           * Define the value in an object at a given string path.
           *
           * ```js
           * var obj = {
           *     prop1: {
           *         arr: ['a', 'b', 'c']
           *       , str: 'Hello'
           *     }
           *   , prop2: {
           *         arr: [ { nested: 'Universe' } ]
           *       , str: 'Hello again!'
           *     }
           * };
           * ```
           *
           * The following would be acceptable.
           *
           * ```js
           * var properties = require('tea-properties');
           * properties.set(obj, 'prop1.str', 'Hello Universe!');
           * properties.set(obj, 'prop1.arr[2]', 'B');
           * properties.set(obj, 'prop2.arr[0].nested.value', { hello: 'universe' });
           * ```
           *
           * @param {Object} object
           * @param {String} path
           * @param {Mixed} value
           * @api private
           */

          function setPathValue(obj, path, val) {
            var parsed = parsePath(path)
            internalSetPathValue(obj, val, parsed)
            return obj
          }

          module.exports = {
            hasProperty: hasProperty,
            getPathInfo: getPathInfo,
            getPathValue: getPathValue,
            setPathValue: setPathValue
          }
        },
        {}
      ],
      39: [
        function (require, module, exports) {
          ;(function (global, factory) {
            typeof exports === 'object' && typeof module !== 'undefined'
              ? (module.exports = factory())
              : typeof define === 'function' && define.amd
              ? define(factory)
              : (global.typeDetect = factory())
          })(this, function () {
            'use strict'

            /* !
             * type-detect
             * Copyright(c) 2013 jake luer <jake@alogicalparadox.com>
             * MIT Licensed
             */
            var promiseExists = typeof Promise === 'function'

            /* eslint-disable no-undef */
            var globalObject = typeof self === 'object' ? self : global // eslint-disable-line id-blacklist

            var symbolExists = typeof Symbol !== 'undefined'
            var mapExists = typeof Map !== 'undefined'
            var setExists = typeof Set !== 'undefined'
            var weakMapExists = typeof WeakMap !== 'undefined'
            var weakSetExists = typeof WeakSet !== 'undefined'
            var dataViewExists = typeof DataView !== 'undefined'
            var symbolIteratorExists =
              symbolExists && typeof Symbol.iterator !== 'undefined'
            var symbolToStringTagExists =
              symbolExists && typeof Symbol.toStringTag !== 'undefined'
            var setEntriesExists =
              setExists && typeof Set.prototype.entries === 'function'
            var mapEntriesExists =
              mapExists && typeof Map.prototype.entries === 'function'
            var setIteratorPrototype =
              setEntriesExists && Object.getPrototypeOf(new Set().entries())
            var mapIteratorPrototype =
              mapEntriesExists && Object.getPrototypeOf(new Map().entries())
            var arrayIteratorExists =
              symbolIteratorExists &&
              typeof Array.prototype[Symbol.iterator] === 'function'
            var arrayIteratorPrototype =
              arrayIteratorExists &&
              Object.getPrototypeOf([][Symbol.iterator]())
            var stringIteratorExists =
              symbolIteratorExists &&
              typeof String.prototype[Symbol.iterator] === 'function'
            var stringIteratorPrototype =
              stringIteratorExists &&
              Object.getPrototypeOf(''[Symbol.iterator]())
            var toStringLeftSliceLength = 8
            var toStringRightSliceLength = -1
            /**
             * ### typeOf (obj)
             *
             * Uses `Object.prototype.toString` to determine the type of an object,
             * normalising behaviour across engine versions & well optimised.
             *
             * @param {Mixed} object
             * @return {String} object type
             * @api public
             */
            function typeDetect(obj) {
              /* ! Speed optimisation
               * Pre:
               *   string literal     x 3,039,035 ops/sec ±1.62% (78 runs sampled)
               *   boolean literal    x 1,424,138 ops/sec ±4.54% (75 runs sampled)
               *   number literal     x 1,653,153 ops/sec ±1.91% (82 runs sampled)
               *   undefined          x 9,978,660 ops/sec ±1.92% (75 runs sampled)
               *   function           x 2,556,769 ops/sec ±1.73% (77 runs sampled)
               * Post:
               *   string literal     x 38,564,796 ops/sec ±1.15% (79 runs sampled)
               *   boolean literal    x 31,148,940 ops/sec ±1.10% (79 runs sampled)
               *   number literal     x 32,679,330 ops/sec ±1.90% (78 runs sampled)
               *   undefined          x 32,363,368 ops/sec ±1.07% (82 runs sampled)
               *   function           x 31,296,870 ops/sec ±0.96% (83 runs sampled)
               */
              var typeofObj = typeof obj
              if (typeofObj !== 'object') {
                return typeofObj
              }

              /* ! Speed optimisation
               * Pre:
               *   null               x 28,645,765 ops/sec ±1.17% (82 runs sampled)
               * Post:
               *   null               x 36,428,962 ops/sec ±1.37% (84 runs sampled)
               */
              if (obj === null) {
                return 'null'
              }

              /* ! Spec Conformance
               * Test: `Object.prototype.toString.call(window)``
               *  - Node === "[object global]"
               *  - Chrome === "[object global]"
               *  - Firefox === "[object Window]"
               *  - PhantomJS === "[object Window]"
               *  - Safari === "[object Window]"
               *  - IE 11 === "[object Window]"
               *  - IE Edge === "[object Window]"
               * Test: `Object.prototype.toString.call(this)``
               *  - Chrome Worker === "[object global]"
               *  - Firefox Worker === "[object DedicatedWorkerGlobalScope]"
               *  - Safari Worker === "[object DedicatedWorkerGlobalScope]"
               *  - IE 11 Worker === "[object WorkerGlobalScope]"
               *  - IE Edge Worker === "[object WorkerGlobalScope]"
               */
              if (obj === globalObject) {
                return 'global'
              }

              /* ! Speed optimisation
               * Pre:
               *   array literal      x 2,888,352 ops/sec ±0.67% (82 runs sampled)
               * Post:
               *   array literal      x 22,479,650 ops/sec ±0.96% (81 runs sampled)
               */
              if (
                Array.isArray(obj) &&
                (symbolToStringTagExists === false ||
                  !(Symbol.toStringTag in obj))
              ) {
                return 'Array'
              }

              // Not caching existence of `window` and related properties due to potential
              // for `window` to be unset before tests in quasi-browser environments.
              if (typeof window === 'object' && window !== null) {
                /* ! Spec Conformance
                 * (https://html.spec.whatwg.org/multipage/browsers.html#location)
                 * WhatWG HTML$7.7.3 - The `Location` interface
                 * Test: `Object.prototype.toString.call(window.location)``
                 *  - IE <=11 === "[object Object]"
                 *  - IE Edge <=13 === "[object Object]"
                 */
                if (
                  typeof window.location === 'object' &&
                  obj === window.location
                ) {
                  return 'Location'
                }

                /* ! Spec Conformance
                 * (https://html.spec.whatwg.org/#document)
                 * WhatWG HTML$3.1.1 - The `Document` object
                 * Note: Most browsers currently adher to the W3C DOM Level 2 spec
                 *       (https://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-26809268)
                 *       which suggests that browsers should use HTMLTableCellElement for
                 *       both TD and TH elements. WhatWG separates these.
                 *       WhatWG HTML states:
                 *         > For historical reasons, Window objects must also have a
                 *         > writable, configurable, non-enumerable property named
                 *         > HTMLDocument whose value is the Document interface object.
                 * Test: `Object.prototype.toString.call(document)``
                 *  - Chrome === "[object HTMLDocument]"
                 *  - Firefox === "[object HTMLDocument]"
                 *  - Safari === "[object HTMLDocument]"
                 *  - IE <=10 === "[object Document]"
                 *  - IE 11 === "[object HTMLDocument]"
                 *  - IE Edge <=13 === "[object HTMLDocument]"
                 */
                if (
                  typeof window.document === 'object' &&
                  obj === window.document
                ) {
                  return 'Document'
                }

                if (typeof window.navigator === 'object') {
                  /* ! Spec Conformance
                   * (https://html.spec.whatwg.org/multipage/webappapis.html#mimetypearray)
                   * WhatWG HTML$8.6.1.5 - Plugins - Interface MimeTypeArray
                   * Test: `Object.prototype.toString.call(navigator.mimeTypes)``
                   *  - IE <=10 === "[object MSMimeTypesCollection]"
                   */
                  if (
                    typeof window.navigator.mimeTypes === 'object' &&
                    obj === window.navigator.mimeTypes
                  ) {
                    return 'MimeTypeArray'
                  }

                  /* ! Spec Conformance
                   * (https://html.spec.whatwg.org/multipage/webappapis.html#pluginarray)
                   * WhatWG HTML$8.6.1.5 - Plugins - Interface PluginArray
                   * Test: `Object.prototype.toString.call(navigator.plugins)``
                   *  - IE <=10 === "[object MSPluginsCollection]"
                   */
                  if (
                    typeof window.navigator.plugins === 'object' &&
                    obj === window.navigator.plugins
                  ) {
                    return 'PluginArray'
                  }
                }

                if (
                  (typeof window.HTMLElement === 'function' ||
                    typeof window.HTMLElement === 'object') &&
                  obj instanceof window.HTMLElement
                ) {
                  /* ! Spec Conformance
                   * (https://html.spec.whatwg.org/multipage/webappapis.html#pluginarray)
                   * WhatWG HTML$4.4.4 - The `blockquote` element - Interface `HTMLQuoteElement`
                   * Test: `Object.prototype.toString.call(document.createElement('blockquote'))``
                   *  - IE <=10 === "[object HTMLBlockElement]"
                   */
                  if (obj.tagName === 'BLOCKQUOTE') {
                    return 'HTMLQuoteElement'
                  }

                  /* ! Spec Conformance
                   * (https://html.spec.whatwg.org/#htmltabledatacellelement)
                   * WhatWG HTML$4.9.9 - The `td` element - Interface `HTMLTableDataCellElement`
                   * Note: Most browsers currently adher to the W3C DOM Level 2 spec
                   *       (https://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-82915075)
                   *       which suggests that browsers should use HTMLTableCellElement for
                   *       both TD and TH elements. WhatWG separates these.
                   * Test: Object.prototype.toString.call(document.createElement('td'))
                   *  - Chrome === "[object HTMLTableCellElement]"
                   *  - Firefox === "[object HTMLTableCellElement]"
                   *  - Safari === "[object HTMLTableCellElement]"
                   */
                  if (obj.tagName === 'TD') {
                    return 'HTMLTableDataCellElement'
                  }

                  /* ! Spec Conformance
                   * (https://html.spec.whatwg.org/#htmltableheadercellelement)
                   * WhatWG HTML$4.9.9 - The `td` element - Interface `HTMLTableHeaderCellElement`
                   * Note: Most browsers currently adher to the W3C DOM Level 2 spec
                   *       (https://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-82915075)
                   *       which suggests that browsers should use HTMLTableCellElement for
                   *       both TD and TH elements. WhatWG separates these.
                   * Test: Object.prototype.toString.call(document.createElement('th'))
                   *  - Chrome === "[object HTMLTableCellElement]"
                   *  - Firefox === "[object HTMLTableCellElement]"
                   *  - Safari === "[object HTMLTableCellElement]"
                   */
                  if (obj.tagName === 'TH') {
                    return 'HTMLTableHeaderCellElement'
                  }
                }
              }

              /* ! Speed optimisation
               * Pre:
               *   Float64Array       x 625,644 ops/sec ±1.58% (80 runs sampled)
               *   Float32Array       x 1,279,852 ops/sec ±2.91% (77 runs sampled)
               *   Uint32Array        x 1,178,185 ops/sec ±1.95% (83 runs sampled)
               *   Uint16Array        x 1,008,380 ops/sec ±2.25% (80 runs sampled)
               *   Uint8Array         x 1,128,040 ops/sec ±2.11% (81 runs sampled)
               *   Int32Array         x 1,170,119 ops/sec ±2.88% (80 runs sampled)
               *   Int16Array         x 1,176,348 ops/sec ±5.79% (86 runs sampled)
               *   Int8Array          x 1,058,707 ops/sec ±4.94% (77 runs sampled)
               *   Uint8ClampedArray  x 1,110,633 ops/sec ±4.20% (80 runs sampled)
               * Post:
               *   Float64Array       x 7,105,671 ops/sec ±13.47% (64 runs sampled)
               *   Float32Array       x 5,887,912 ops/sec ±1.46% (82 runs sampled)
               *   Uint32Array        x 6,491,661 ops/sec ±1.76% (79 runs sampled)
               *   Uint16Array        x 6,559,795 ops/sec ±1.67% (82 runs sampled)
               *   Uint8Array         x 6,463,966 ops/sec ±1.43% (85 runs sampled)
               *   Int32Array         x 5,641,841 ops/sec ±3.49% (81 runs sampled)
               *   Int16Array         x 6,583,511 ops/sec ±1.98% (80 runs sampled)
               *   Int8Array          x 6,606,078 ops/sec ±1.74% (81 runs sampled)
               *   Uint8ClampedArray  x 6,602,224 ops/sec ±1.77% (83 runs sampled)
               */
              var stringTag = symbolToStringTagExists && obj[Symbol.toStringTag]
              if (typeof stringTag === 'string') {
                return stringTag
              }

              var objPrototype = Object.getPrototypeOf(obj)
              /* ! Speed optimisation
               * Pre:
               *   regex literal      x 1,772,385 ops/sec ±1.85% (77 runs sampled)
               *   regex constructor  x 2,143,634 ops/sec ±2.46% (78 runs sampled)
               * Post:
               *   regex literal      x 3,928,009 ops/sec ±0.65% (78 runs sampled)
               *   regex constructor  x 3,931,108 ops/sec ±0.58% (84 runs sampled)
               */
              if (objPrototype === RegExp.prototype) {
                return 'RegExp'
              }

              /* ! Speed optimisation
               * Pre:
               *   date               x 2,130,074 ops/sec ±4.42% (68 runs sampled)
               * Post:
               *   date               x 3,953,779 ops/sec ±1.35% (77 runs sampled)
               */
              if (objPrototype === Date.prototype) {
                return 'Date'
              }

              /* ! Spec Conformance
               * (http://www.ecma-international.org/ecma-262/6.0/index.html#sec-promise.prototype-@@tostringtag)
               * ES6$25.4.5.4 - Promise.prototype[@@toStringTag] should be "Promise":
               * Test: `Object.prototype.toString.call(Promise.resolve())``
               *  - Chrome <=47 === "[object Object]"
               *  - Edge <=20 === "[object Object]"
               *  - Firefox 29-Latest === "[object Promise]"
               *  - Safari 7.1-Latest === "[object Promise]"
               */
              if (promiseExists && objPrototype === Promise.prototype) {
                return 'Promise'
              }

              /* ! Speed optimisation
               * Pre:
               *   set                x 2,222,186 ops/sec ±1.31% (82 runs sampled)
               * Post:
               *   set                x 4,545,879 ops/sec ±1.13% (83 runs sampled)
               */
              if (setExists && objPrototype === Set.prototype) {
                return 'Set'
              }

              /* ! Speed optimisation
               * Pre:
               *   map                x 2,396,842 ops/sec ±1.59% (81 runs sampled)
               * Post:
               *   map                x 4,183,945 ops/sec ±6.59% (82 runs sampled)
               */
              if (mapExists && objPrototype === Map.prototype) {
                return 'Map'
              }

              /* ! Speed optimisation
               * Pre:
               *   weakset            x 1,323,220 ops/sec ±2.17% (76 runs sampled)
               * Post:
               *   weakset            x 4,237,510 ops/sec ±2.01% (77 runs sampled)
               */
              if (weakSetExists && objPrototype === WeakSet.prototype) {
                return 'WeakSet'
              }

              /* ! Speed optimisation
               * Pre:
               *   weakmap            x 1,500,260 ops/sec ±2.02% (78 runs sampled)
               * Post:
               *   weakmap            x 3,881,384 ops/sec ±1.45% (82 runs sampled)
               */
              if (weakMapExists && objPrototype === WeakMap.prototype) {
                return 'WeakMap'
              }

              /* ! Spec Conformance
               * (http://www.ecma-international.org/ecma-262/6.0/index.html#sec-dataview.prototype-@@tostringtag)
               * ES6$24.2.4.21 - DataView.prototype[@@toStringTag] should be "DataView":
               * Test: `Object.prototype.toString.call(new DataView(new ArrayBuffer(1)))``
               *  - Edge <=13 === "[object Object]"
               */
              if (dataViewExists && objPrototype === DataView.prototype) {
                return 'DataView'
              }

              /* ! Spec Conformance
               * (http://www.ecma-international.org/ecma-262/6.0/index.html#sec-%mapiteratorprototype%-@@tostringtag)
               * ES6$23.1.5.2.2 - %MapIteratorPrototype%[@@toStringTag] should be "Map Iterator":
               * Test: `Object.prototype.toString.call(new Map().entries())``
               *  - Edge <=13 === "[object Object]"
               */
              if (mapExists && objPrototype === mapIteratorPrototype) {
                return 'Map Iterator'
              }

              /* ! Spec Conformance
               * (http://www.ecma-international.org/ecma-262/6.0/index.html#sec-%setiteratorprototype%-@@tostringtag)
               * ES6$23.2.5.2.2 - %SetIteratorPrototype%[@@toStringTag] should be "Set Iterator":
               * Test: `Object.prototype.toString.call(new Set().entries())``
               *  - Edge <=13 === "[object Object]"
               */
              if (setExists && objPrototype === setIteratorPrototype) {
                return 'Set Iterator'
              }

              /* ! Spec Conformance
               * (http://www.ecma-international.org/ecma-262/6.0/index.html#sec-%arrayiteratorprototype%-@@tostringtag)
               * ES6$22.1.5.2.2 - %ArrayIteratorPrototype%[@@toStringTag] should be "Array Iterator":
               * Test: `Object.prototype.toString.call([][Symbol.iterator]())``
               *  - Edge <=13 === "[object Object]"
               */
              if (
                arrayIteratorExists &&
                objPrototype === arrayIteratorPrototype
              ) {
                return 'Array Iterator'
              }

              /* ! Spec Conformance
               * (http://www.ecma-international.org/ecma-262/6.0/index.html#sec-%stringiteratorprototype%-@@tostringtag)
               * ES6$21.1.5.2.2 - %StringIteratorPrototype%[@@toStringTag] should be "String Iterator":
               * Test: `Object.prototype.toString.call(''[Symbol.iterator]())``
               *  - Edge <=13 === "[object Object]"
               */
              if (
                stringIteratorExists &&
                objPrototype === stringIteratorPrototype
              ) {
                return 'String Iterator'
              }

              /* ! Speed optimisation
               * Pre:
               *   object from null   x 2,424,320 ops/sec ±1.67% (76 runs sampled)
               * Post:
               *   object from null   x 5,838,000 ops/sec ±0.99% (84 runs sampled)
               */
              if (objPrototype === null) {
                return 'Object'
              }

              return Object.prototype.toString
                .call(obj)
                .slice(toStringLeftSliceLength, toStringRightSliceLength)
            }

            return typeDetect
          })
        },
        {}
      ]
    },
    {},
    [1]
  )(1)
})
