input: def count_vowels(string: str) -> int: 
      """
      Given a string, this function returns the total number of vowels in the string.
      >>> count_vowels("hello")
      2
      >>> count_vowels("WORLD")
      1
      >>> count_vowels("Python Programming")
      4
      """
      vowels = "aeiou"
      count = 0
      for s in string:
          if s.lower() in vowels:
              count += 1
      return count
output:     vowels = "aeiou"
      count = 0
      for s in string:
          if s.lower() in vowels:
              count += 1
      return count