input: Write a function to swap the values of two variables. The function should return the new values of the variables after they have been swapped.
  assert swap_variables(5, 10) == (10, 5)
  assert swap_variables(2, 3) == (3, 2)
  assert swap_variables("a", "b") == ("b", "a")
output: def swap_variables(a, b):
      return b, a