Implement the function which should return `true` if given object is a vowel (meaning `a, e, i, o, u`), and `false` otherwise.
def is_vowel(s): 
    return True if s.lower() in ['a', 'e', 'i', 'u', 'o'] else False
def is_vowel(s): 
    return True if s.lower() in ['a', 'e', 'i', 'u', 'o'] else False