Hi, is there someone available who would be willing to review this please? Maybe @markshannon as the original author of these flags?

Please create an issue to discuss this change. Thanks

That comment doesn't look like it's describing the flags itself, but instead whether they should be present as public constants in collections.abc itself, which it shouldn't. Type flags aren't part of the language, just the C API.

Instead of using the flags, an alternative for the equivalent functionality would be to do the same way Python code does - import collections.abc.Mapping/Sequence, then call .register() or PyObject_IsInstance()/PyObject_IsSubclass(). Less performant of course, but it'll work on pretty much any Python version.

I don't think these flags should be part of the stable API.

As @TeamSpen210 says, using collections.abc.Sequence.register() is more robust, as it ensures consistency of flags and abstract base class.

Understood, thanks for the feedback - will close this 👍