input: def reverse_words(str: str) -> str:
      """Reverse the order of words in a given string.
      
      >>> reverse_words("Hello world")
      'world Hello'
      >>> reverse_words("Python is awesome")
      'awesome is Python'
      """
output:     words = str.split()
      reversed_words = words[::-1]
      return ' '.join(reversed_words)