input: Write a function to extract the non-vowel words from a given sentence. If the sentence contains no words or all words contain vowels, return an empty list. If the sentence contains non-vowel words, return the list of those words. The function should be case-insensitive.
  assert extract_words("This machine learning project is challenging.")==['This', 'machine', 'learning', 'project', 'is', 'challenging.']
  assert extract_words("Python programming is fun")==['Python', 'programming', 'fun']
  assert extract_words("AEIOU aeiou")==[]
  assert extract_words("")==[]
  assert extract_words("BCDFG bcdfg")==['BCDFG', 'bcdfg']
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