In Python, how to swap two numbers without using a temp variable

This is a very interesting question: How to swap two number variables without using a temp variable?

I have actually been asked this question while being interviewed for a job. Also this is a very well-known coding interview questions; therefore some books of interview preparation cover this question, for example, Cracking the Coding Interview. The answer is here.

 x = x + y;  // x now becomes 15

  y = x - y;  // y becomes 10

  x = x - y;  // x becomes 5

However, while I was studying Problem Solving with Algorithms and Data Structures using Python, I found that in Python, this problem can be solved so simple as below:

left, right = right, left

You can check how this works here.