While reading the Binary trees chapter from Programming Interviews Exposed by John Mongan et al. I started thinking of alternative recursion examples which do not involve sorting, generating Fibonacci sequence, binary tree traversal and similar tasks. Lisp! Lisp is inseparable from recursion and Lisp interpreter would be a good case to demonstrate what recursion is and how it can be used efficiently. What would be a minimal simplified Lisp interpreter written in Python? Surprisingly, I managed to do it just in 6 lines of Python code! And this is not just because of Python being a wonderful language, but because of Lisp being such a beautiful and simple concept.