Leap Years
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http://cyber-dojo.org/setup/show_exercises/?language=C%2B%2B%20(clang%2B%2B)&test=GoogleTest


Write a function that returns true or false depending on
whether its input integer is a leap year or not.

A leap year is defined as one that is divisible by 4,
but is not otherwise divisible by 100 unless it is
also divisible by 400.

For example, 2001 is a typical common year and 1996
is a typical leap year, whereas 1900 is an atypical
common year and 2000 is an atypical leap year.
