input: def filter_vowels(string: str) -> str:
      """Filters out all the vowels from a given string.
      
      >>> filter_vowels("hello world")
      'hll wrld'
      
      >>> filter_vowels("aeiou")
      ''
      
      >>> filter_vowels("Python Programming")
      'Pythn Progrmmng'
      """
output:     vowels = "aeiouAEIOU"
      filtered_string = ''.join([char for char in string if char not in vowels])
      return filtered_string