Norvig's notebooks are my favorite resource for code reading. He has so much of them, written is such a nice, clean, clever but yet understandable and readable way, it's always a pleasure and amazing learning experience to go through them.

For example, going through his notebook for code advent (the first linked) [1].

[1] https://nbviewer.jupyter.org/url/norvig.com/ipython/Advent%2...