Recursion can be tricky to grasp. Professor Thorsten Altenkirch uses Python to demonstrate an example taken from his latest book. More on recursion:    • Recursion Explained   EXTRA BITS: https://www.youtube.com/watch?v=c9IH8DHDI4M Thorsten & Isaac's Python programming book: https://bit.ly/2p3r5IT https://www.facebook.com/computerphile https://twitter.com/computer_phile This video was filmed and edited by Sean Riley. Computer Science at the University of Nottingham: https://bit.ly/nottscomputer Computerphile is a sister project to Brady Haran's Numberphile. More at http://www.bradyharan.com/