input: from typing import List
  
  def reverse_words(str):
      return " ".join(str.split()[::-1])
  
  """
  Reverse the order of words in a given string.
  
  >>> reverse_words("Python is fun")
  'fun is Python'
  >>> reverse_words("I love coding in Python")
  'Python in coding love I'
  >>> reverse_words("")
  ''
  """
output:     return " ".join(str.split()[::-1])