python: 3
I'm assuming you agree (or will consider) that adding some type-checking to your Python code can help you find bugs or otherwise improve your software. You've definitely heard of mypy, and possibly one or more of pytype, pyre, and pyright. That's a lot of options! What should you use?
I gave a talk at PyColorado 2019! Thank you to Frank, Scott, Emily, the Cuttlesoft team, and everyone else at PyColorado for an awesome event!
A little while ago, I encountered a blog post that's stuck in my head ever since -- Adam Drake's experiment with command-line tools for data processing. Ever since then, I've wanted to do a little experimenting of my own. I finally got around to it this evening.