But function isn't actually a recognized name in Python. Instead, you'll need to use the typing module, which comes with Python 3 so you can do this kind of type checking.

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.

Python 3 introduced the idea of "type annotations," and as of Python 3.6, you can annotate variables, not just function parameters and return values. The idea is that you can put a colon (:) and then ...

Python comes with a collection of built-in data types that make common data-wrangling operations easy. Among them is the list, a simple but versatile collection type.