input: Write a function to print the strings "Hello" and "World" in the same line. The function should store the strings in variables and concatenate them with a space in between before printing.
  
  assert print_hello_world()=="Hello World"
output: def print_hello_world():
      str1 = "Hello"
      str2 = "World"
      result = str1 + " " + str2
      return result