First i love the visualizations. It grew on me. And supportive of coding challenges posts. As long as there isn’t a flood of them. Which there isn’t.

I get your position. That there just isn’t an explanation for each and every exercise. The other comments made it seemed like there was.

When i clicked on the Explanation link, the browser didn’t initially scroll to the Mutability section. Went downhill from there.

btw i’m too dumb to know the answer and too lazy to copy+paste the code into a REPR.

All the other commenters are just dishonest pretending they totally got it without running the code ;-)