input: Write a function to store the strings "Hello" and "World" in variables and print them in the same line. If the strings are not provided, use the default values "Hello" and "World".
  
  def print_strings(string1="Hello", string2="World"):
      print(string1 + " " + string2)
  
  assert print_strings() == None
  assert print_strings("Hi", "There") == None
output: def print_strings(string1="Hello", string2="World"):
      print(string1 + " " + string2)