[$] A "frozen" dictionary for Python

Dictionaries are ubiquitous in Python code; they are the data structure ofchoice for a wide variety of tasks. But dictionaries are mutable, whichmakes them problematic for sharing data in concurrent code. Python hasadded various concurrency features to the language over the last decade orso-async, free threading without the global interpreter lock(GIL), and independent subinterpreters-but users must work out their ownsolution for an immutable dictionary that can be safely shared byconcurrent code. There are existing modules that could be used, but a recent proposal, PEP 814 ("Add frozendictbuilt-in type"), looks to bring the feature to the language itself.