input: Write a function to swap the values of two variables in Python. If the variables are x and y, the function should return the values of x and y after swapping.
  assert swap_variables(5, 10) == (10, 5)
  assert swap_variables(2, 7) == (7, 2)
  assert swap_variables("a", "b") == ("b", "a")
  assert swap_variables(True, False) == (False, True)
  assert swap_variables([1, 2], [3, 4]) == ([3, 4], [1, 2])
output: def swap_variables(x, y):
      return y, x