input: Write a function to extract the non-vowel words from a given sentence. The function should return a list of words that do not contain any vowel characters. If the sentence is empty, the function should return an empty list.
  assert extract_words("This machine learning project is challenging.")==['Ths', 'mchn', 'lrnng', 'prjct', 's', 'chlngng']
  assert extract_words("Python is easy to learn.")==['Pythn', 's', 'ys', 't']
  assert extract_words("")==[]
output: def extract_words(sentence):
      vowels = "aeiouAEIOU"
      words = sentence.split()
      non_vowel_words = [word for word in words if not any(char in vowels for char in word)]
      return non_vowel_words