input: Write a python function to classify a list of words into two categories depending on their length.
  assert classify_words(["apple", "banana", "cherry", "date", "elderberry"]) == (["apple", "date"], ["banana", "cherry", "elderberry"])
  assert classify_words(["cat", "dog", "elephant", "frog"]) == (["cat", "dog", "frog"], ["elephant"])
  assert classify_words(["short", "tiny", "massive", "huge"]) == (["short", "tiny"], ["massive", "huge"])
output: def classify_words(words):
      short_words = [word for word in words if len(word) <= 4]
      long_words = [word for word in words if len(word) > 4]
      return (short_words, long_words)