Gradual typing was introduced in Python 3.5 standard library. Since then a lot of standard library changes, new PEPs, third-party libraries added support to type-hints. The flask 2.0 supports type-hints, SQLAlchemy, Django(through the third-party stubs ) and a lot more of the libraries support gradual typing.
The resources to learn gradual typing are minimal and available in form of talks. I have built a self-exploratory way to learn Python typing using the TDD/koans concept, [Python Typing Koans](https://github.com/kracekumar/python-typing-koans).
The materials has koans for learn typing the pure python code, Django code, Django Rest Framework.
[Here is a small demo video](https://asciinema.org/a/419119)
In this 10 minutes talk, I'll show how to use the tool to learn gradual typing with hand-picked examples from a wide range of topics by adding/modifying the existing Python code and type-annotation.
Note: Gradual typing, type-hints, optional static typing all refers to the same concept.