input: 
  def filter_vowels(string: str) -> str:
      """Filters out all the vowels from the given string and returns the modified string.
      
      >>> filter_vowels("hello world")
      'hll wrld'
      >>> filter_vowels("aeiou")
      ''
      >>> filter_vowels("bcdfghjkl")
      'bcdfghjkl'
      """
  
output:     vowels = "aeiouAEIOU"
      return ''.join([char for char in string if char not in vowels])