I remember writing this kind of stuff. Couple years after I left they'd re-written it, just so they would have somebody who understood it. My friend reported their engineer visiting his office often to exclaim over something he now understood!

It helps to rewrite something with example code in hand. You end up understanding everything.

(I did not mean to be opaque; we were a startup and it was hurry-up-and-be-done-yesterday code)