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.
  
  assert extract_words("This machine learning project is challenging.")==['prjct', 'is']
  assert extract_words("The quick brown fox jumps over the lazy dog.")==['brwn','fx','jumps','over','th','lz','dg']
  assert extract_words("Python")==[]
  assert extract_words("")==[]
output: def extract_words(sentence):
      vowels = "aeiouAEIOU"
      return [word for word in sentence.split() if not any(char in vowels for char in word)]