Kata

Check if it is a vowel(a, e, i, o, u,) on the n position in a string (the first argument). Don't forget about uppercase.

A few cases:

{
checkVowel('cat', 1)  ->   true // 'a' is a vowel
checkVowel('cat', 0)  ->   false // 'c' is not a vowel
checkVowel('cat', 4)  ->   false // this position doesn't exist
}

P.S. If n < 0, return false