Swapping values of two variables

[Eric Kang]

In python, I set:

x=1
y=3

z = x
x = y
y = z


This gave me 3 1, which are the values of x and y swapped.
The following would have given me the same result:
x, y = y, x



But could the swapping be done using less extra memory than this? What is the minimum amount of extra memory required to exchange two 32-bit quantities? What would be the pseudocode that achieves this minimum?