input: Write a function to filter out all the vowels from a given string. The function should return a new string with all vowel characters removed.
  
  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("aeiouAEIOU")==""
  assert filter_vowels("")==""
  assert filter_vowels("bcdfghjklmnpqrstvwxyz")=="bcdfghjklmnpqrstvwxyz"
output: def filter_vowels(string):
      vowels = ('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U')
      return ''.join(c for c in string if c not in vowels)