input: def remove_vowels(string: str) -> str:
      """Remove all vowels from the given string.
      >>> remove_vowels('hello world')
      'hll wrld'
      >>> remove_vowels('AEIOUaeiou')
      ''
      >>> remove_vowels('Python Programming')
      'Pythn Prgrmmng'
      """
output:     vowels = "AEIOUaeiou"
      result = [char for char in string if char not in vowels]
      return ''.join(result)