input: Write a function to filter out all the vowels from a given string. If the input string is empty, return an empty string.
  assert filter_vowels("hello world")=="hll wrld"
  assert filter_vowels("python programming")=="pythn prgrmmng"
  assert filter_vowels("aeiou")==""
  assert filter_vowels("")==""
  def filter_vowels(string):
      vowels = ('a', 'e', 'i', 'o', 'u')
      return ''.join(c for c in string if c not in vowels)
output: def filter_vowels(string):
      vowels = ('a', 'e', 'i', 'o', 'u')
      return ''.join(c for c in string if c not in vowels)