input: Write a function to print "Hello World!" five times.
  def hello_world_five_times():
      for x in range(5):
          print("Hello World!")
  
  assert hello_world_five_times() is None
  assert hello_world_five_times() is None
                          
output: def hello_world_five_times():
      for x in range(5):
          print("Hello World!")