Ooh that's really pretty. I was going to bring up the IPython notebook functionality, in part because it was used as a follow-up to another xkcd strip ("Regex

Ooh that's really pretty. I was going to bring up the IPython notebook functionality, in part because it was used as a follow-up to another xkcd strip ("Regex Golf", http://nbviewer.ipython.org/url/norvig.com/ipython/xkcd1313.ipynb http://nbviewer.ipython.org/url/norvig.com/ipython/xkcd1313.... ), but I gotta say that one looks nicer :) The use-cases are slightly different, though.