input: Write a function to reverse the order of words in a given sentence while keeping the order of the characters in each word the same.
  
  def reverse_words(sentence):
      words = sentence.split()
      reversed_sentence = ' '.join(reversed(words))
      return reversed_sentence
  
  assert reverse_words("This is a sentence.") == "sentence. a is This"
  assert reverse_words("Hello world") == "world Hello"
  assert reverse_words("Python is fun") == "fun is Python"
  assert reverse_words("Quick brown fox") == "fox brown Quick"
  assert reverse_words("SingleWord") == "SingleWord"
  assert reverse_words("") == ""
  assert reverse_words("Multiple    spaces are   here") == "here   are spaces    Multiple"
output: def reverse_words(sentence):
      words = sentence.split()
      reversed_sentence = ' '.join(reversed(words))
      return reversed_sentence