Yesterday I've published this video where I share a few tips on how to dive into third-party #lisp code:
YouTube: https://www.youtube.com/watch?v=WlXJi6aOb2M
Fediverse: https://diode.zone/w/i3rftca5wfChpycvxPsQA9
Watch till the end of the clip, to learn how to remove multi-methods in runtime! :)