input:  python
  def swap_variables(x: int, y: int) -> tuple:
      """Swaps the values of two variables and returns them.
      >>> swap_variables(5, 10)
      (10, 5)
      >>> swap_variables(0, -1)
      (-1, 0)
      """
      x, y = y, x
      return (x, y)
  
output:     x, y = y, x
      return (x, y)