You are given two lists: letters contains the letters of the Latin alphabet and vowels contains only the vowels ['a', 'e', 'i', 'u', 'o'].
Define a function choose_vowels() that, given the list letters, would return only those letters that are vowels. You do NOT need to call the function or take any input.
Sample of the list letters:
['p', 'r', 'o', 'g', 'r', 'a', 'm', 'm', 'i', 'n', 'g', 'l', 'a', 'n', 'g', 'u', 'a', 'g', 'e']
Sample output:
['o', 'a', 'i', 'a', 'u', 'a', 'e']
