input: 
  def print_greeting() -> None:
      """Prints the strings "Hello" and "World" in the same line.
      >>> print_greeting()
      Hello World
      """
      string1 = "Hello"
      string2 = "World"
      print(string1 + " " + string2)
  
output:     string1 = "Hello"
      string2 = "World"
      print(string1 + " " + string2)