input: Write a function that reverses the order of words in a given sentence while keeping the order of characters in each word unchanged.
  def reverse_order(sentence):
    words = sentence.split()
    reversed_sentence = ' '.join(reversed(words))
    return reversed_sentence
  
  assert reverse_order("This is a test") == "test a is This"
  assert reverse_order("Hello world") == "world Hello"
  assert reverse_order("SingleWord") == "SingleWord"
  assert reverse_order("") == ""
  assert reverse_order("    ") == ""
output: def reverse_order(sentence):
    words = sentence.split()
    reversed_sentence = ' '.join(reversed(words))
    return reversed_sentence