But annotating four million lines of Python code in this way isn’t a straightforward task, here are some of the lesser-known benefits and how Dropbox accomplished the task.

Here’s one that exists in about 150 lines of Python code. You might wonder what the value is. After all, there are plenty of well-done simulators including Quirk that we have looked at in the past.

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.