input: def reverse_words(sentence: str) -> str:
      """
      Reverse the order of words in a sentence but keep the order of the characters in each word the same.
      
      >>> reverse_words('This is a sentence.')
      'sentence. a is This'
      >>> reverse_words('Hello world!')
      'world! Hello'
      """
      words = sentence.split()
      reversed_sentence = ' '.join(words[::-1])
      return reversed_sentence
output:     words = sentence.split()
      reversed_sentence = ' '.join(words[::-1])
      return reversed_sentence