input: Write a function to extract the non-vowel words in a sentence. The function takes a sentence as input and returns a list of words that do not contain any vowels. If the input sentence is empty, the function should return an empty list.
  assert extract_words("This machine learning project is challenging.")==['Ths', 'mch', 'ln', 'pr', 'ch', 'llng']
  assert extract_words("Hello World")==['Hll', 'Wrld']
  assert extract_words("Python Programming")==['Pythn', 'Prgrmmng']
  assert extract_words("")==[]
output: def extract_words(sentence):
      vowels = "aeiouAEIOU"
      words = sentence.split()
      non_vowel_words = [word for word in words if all(char not in vowels for char in word)]
      return non_vowel_words