if-let, when-let, thread-first and thread-last
Good little introduction to flow control macros that were introduced in Emacs 25.1.
Possible replacement for pipenv. Seems to do a lot of what I would need, and perhaps some more; but also appears to be missing some things I do find useful about pipenv.
For example: I do like how pipenv sweeps up the whole venv thing in what feels like a sensible way. poetry doesn't appear to handle that sort of thing (by design, as far as I can tell).