Worth noting from <https://devclass.com/2020/10/06/python-3_9/>: * Merging of dictionaries with “|” and “|=” operators * Generics in type hints * General expressions now allowed in decorators (I didn’t actually realize there were restrictions before) * New PEG parser, with option to revert to old parser for now (not that I expect to notice any difference between the two) * Deprecation of features for Python 2 backward compatibility (to be removed altogether in 3.10)