input: def swap_values(x: int, y: int) -> tuple[int, int]:
      """ Swaps the values of two variables.
      >>> swap_values(5, 10)
      (10, 5)
      >>> swap_values(0, -1)
      (-1, 0)
      """
      x, y = y, x
      return x, y
output:     x, y = y, x
      return x, y