input: def filter_vowels(string: str) -> str:
      """Filter out all the vowels from a given string.
      >>> 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])