input: Write a function to filter out all the vowels from a string. The function should return a new string with all vowels removed. If the input string is empty, the function should return an 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")=="hll"
  assert filter_vowels("world")=="wrld"
  assert filter_vowels("aeiou")==""
  assert filter_vowels("python")=="pythn"
  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)