[kstrauser]

Note: in practice, almost no one uses map, filter, and reduce. Those are almost 100% replaced by list and generator comprehensions in code written in the last decade or so.

The difference between split and join is kind of weird, I'll grant. I'm not sure why it was done that way.

`sort` is in place. You're telling an object to order itself: "hey you! Sort yourself!" `sorted` returns a copy of an object, but... sorted. You're asking for the sorted version of that thing.