Exercise: vowels

Write a function count_vowels(text) that returns how many Latin vowels a, e, i, o and u the string text contains. Uppercase vowels count too.

• count_vowels("Hello") → 2
• count_vowels("AEIOU aeiou") → 10
• count_vowels("rhythm") → 0

Constraints: text consists of Latin letters, digits, spaces and punctuation and may be an empty string; the letter y is not a vowel.

Do not add extra imports unless the task says so explicitly.