Great point. On a similar note, I've gotten a lot of use out of stepping through Python algorithmic code using PythonTutor [1], which maintains a visual dashboard of stack frames/variables and heap objects. Very useful, was just using it earlier today.

Doing this manually with a pencil and paper is arguably even better for learning purposes, although significantly more arduous. I should try it.

1. http://pythontutor.com/