input: Write a function to extract words from a sentence 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("Pythn prgrmng lngugr strctrs nd dply.")==['Pythn', 'prgrmng', 'lngugr', 'strctrs', 'nd', 'dply.']
  assert extract_words("")==[]
  def extract_words(sentence):
      non_vowel_words = []
      words = sentence.split()
      vowels = ['a','e','i','o','u','A','E','I','O','U']
      for word in words:
          if not any(char in vowels for char in word):
              non_vowel_words.append(word) 
      return non_vowel_words
output: def extract_words(sentence):
      non_vowel_words = []
      words = sentence.split()
      vowels = ['a','e','i','o','u','A','E','I','O','U']
      for word in words:
          if not any(char in vowels for char in word):
              non_vowel_words.append(word)
      return non_vowel_words