### countVowels

Retuns `number` of vowels in provided string.

Use a regular expression to count number of vowels `(A, E, I, O, U)` in a `string`.

```js
const countVowels = str => (str.match(/[aeiou]/ig) || []).length;
// countVowels('foobar') -> 3
// countVowels('gym') -> 0
```