input: Write a function to store the strings "Hello" and "World" as variables string1 and string2 respectively, and then print them on the same line separated by a space. 
  
  assert print_hello_world()==None
  # The output should be "Hello World"
  assert print_hello_world.__code__.co_varnames==('string1', 'string2')
output: def print_hello_world():
      string1 = "Hello"
      string2 = "World"
      print(string1, string2)