[XorNot]

Python 3.6's optional types are pretty great. Block out your solution first then start constraining it where you need to.

[icebraining]

+1, I recently wrote some data extraction and processing code using pandas and mypy, and it was pretty great. And progress is happening to add types to numpy and pandas themselves.

[riku_iki]

You still have many not type annotated libraries in ecosystem, and poor support of refactoring/navigation in IDEs.