gh-104050: Improve some typing around `default`s and sentinel values by AlexWaygood · Pull Request #104626 · python/cpython

Not sure if converting the unspecified and unknown sentinels to become enum members is entirely worth it; now that default is typed as object anywhere, the benefits aren't so obvious. I do think it still makes the code a little cleaner, but you tell me whether you think it's worth the churn @erlend-aasland :)

IMO, the more readable we can get clinic.py, the better. We should thread a little careful here, since test_clinic has pretty low coverage. Some of the paths modified are not tested. However, the CI does make clinic (for the check-generated-files job), and that would blow up if semantics changed for the code in question, so we're fine for now.