Commenting your code is good practice if you want to help other people understand what you’ve written. This makes it crucial to learn how to comment in Python if you work on a big team.

Mypy, Pytype, Pyright, and Pyre can help you keep your type-hinted Python code bug-free. Let’s see what each of these useful tools has to offer.

Pyrefly is not the first Python type-checking tool from Meta. Previously, the company delivered Pyre, written in OCaml. Pyre has since been retired; Pyrefly, written from scratch in Rust, replaces it.

I've grabbed Sequence from the typing module, which includes all three Python sequence types—strings, lists and tuples. Once I do that, all of the mypy problems disappear, because all of the arguments ...