input: Write a python function to filter words from a list that contain less than two words.
  assert filter_words(["Hello", "Hi", "two words", "text string", "more than two words!"]) == ["Hello", "Hi"]
  assert filter_words(["single", "two words", "another single"]) == ["single", "another single"]
  assert filter_words(["word", "phrase with two words", "another phrase"]) == ["word"]
output: def filter_words(words):
      return [word for word in words if len(word.split()) < 2]