input: def swap_variables(x: int, y: int) -> None:
      """Swaps the values of two variables and prints the result.
      >>> swap_variables(5, 10)
      x: 10
      y: 5
      >>> swap_variables(0, -1)
      x: -1
      y: 0
      """
      x, y = y, x
      print("x:", x)
      print("y:", y)
output:     x, y = y, x
      print("x:", x)
      print("y:", y)