input: Write a python function to swap the values of two pairs of variables.
  assert swap_values("Alice", "Charlie", 24, 28) == ("Charlie", "Alice", 28, 24)
  assert swap_values("Bob", "Eve", 30, 35) == ("Eve", "Bob", 35, 30)
  assert swap_values("John", "Doe", 40, 50) == ("Doe", "John", 50, 40)
output: def swap_values(a, b, x, y):
      return b, a, y, x