Python has a module called doctest in it’s standard library that will search for usage examples in your documentation and check that they work as shown. This means you can copy and paste snippets from the interactive shell, and ensure that they’re kept up to date.
Stuff about Programming
I stumbled across this blog post by Chris Beams, it has a very clear explanation of the way git expects commit messages to be formatted. Being able to place explanatory paragraphs, links, pasted error output etc really improves the history of my repos. It was always a struggle with CVS and SVN choosing between an extremely long commit message or losing context. The tools are able to distinguish the title from the description too and so can choose how and where to display them as appropriate.
The Decimal class in the standard library is the way to avoid double precision errors in Python.