input: Write a function to store two strings "Hello" and "World" and print them in the same line with a space in between. The function should return None.
  
  assert print_strings() is None
  assert print_strings() is None
  assert print_strings() is None
  assert print_strings() is None
  assert print_strings() is None
output: def print_strings():
      print("Hello World")
      return None