input: def filter_vowels(string: str) -> str:
      """ Given a string, return a new string with all the vowels (a, e, i, o, u) removed.
      >>> filter_vowels('hello world')
      'hll wrld'
      >>> filter_vowels('python programming')
      'pythn prgrmmng'
      """
output:     vowels = "aeiouAEIOU"
      return ''.join([char for char in string if char not in vowels])