Previous PEPs to add pattern matching — PEP 275 and PEP 3103, proposed in 2001 and 2006 respectively — were turned down due to lack of popular support. PEP 3103 was drafted by Python creator ...

A minor but useful recent addition to Python’s syntax, positional-only parameters, lets you indicate which function parameters must be specified as positional ones, never as keyword arguments.

Python 3.9’s PEG-based parser removed these barriers, which long-term could lead to more elegant syntax — our first example of this change is the new parenthesized context managers.