input: Write a function to extract the non-vowel words in a given sentence. Return a list of words that do not contain any vowels. If the sentence is empty, return an empty list.
  assert extract_words("This machine learning project is challenging.")==['This', 'machine', 'learning', 'project', 'is', 'challenging']
  assert extract_words("Brrr mph mnstr")==['Brrr', 'mph', 'mnstr']
  assert extract_words("AEIOU aeiou")==[]
  assert extract_words("")==[]
output: def extract_words(sentence):
      vowels = "aeiouAEIOU"
      words = sentence.split()
      return [word for word in words if all(char not in vowels for char in word)]