I don't think python particularly handles image based programming very well (not that all Lisps do this exclusively, just that they support it well enough for SLIME to make sense). Right now I have a load of code in Python which I'm constantly changing and reloading into my iPython session and it can be a bit of a pain, my files are littered with "reload(x)" statements just so when I reload one the others also get reloaded. I've tried the deep-reload extension to iPython without much success but maybe this will help in the future.