
Write the `capitalize()` function that takes a non-empty string and converts the first letter of the first word to uppercase:

```javascript
const name = 'arya';
console.log(capitalize(name)); // => "Arya"
```

To get a substring (or character) from a string, use the [slice()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice) method:

```javascript
'welcome'.slice(2, 5); // "lco"
```

To convert the string to uppercase, use the [toUpperCase()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase) method:

```javascript
'welcome'.toUpperCase(); // "WELCOME"
```
