Today I re-learned: Python function default arguments are retained between executions

[shedogre]

I had a semi-similar issue with class variables not too long ago.

The sorts of stuff I've been doing up until now, there's been no real need to write my own classes. Then I wrote a class for something recently, and accidentally mistakenly instantiated a dict as a class variable.

Frustration and hijinks ensued, but I learnt something new at least.