input: Write a function to filter out all the vowels from a given string and return the modified string. If the input string is empty, return the empty string.
  def filter_vowels(string):
       vowels = ('a', 'e', 'i', 'o', 'u')
       return ''.join(c for c in string if c not in vowels)
  assert filter_vowels("Hello World!")=="Hll Wrld"
  assert filter_vowels("Python Programming")=="Pythn Prgrmmng"
  assert filter_vowels("aiou")==""
  assert filter_vowels("")==""
output: def filter_vowels(string):
       vowels = ('a', 'e', 'i', 'o', 'u')
       return ''.join(c for c in string if c not in vowels)