[$] Using the limited C API for the Python stdlib?

The 'limited' C API for CPython extensions has been around for well over a
decade at this point, but it has not seen much uptake. It is meant to give
extensions an API that will allow binaries built with it to be used for
multiple versions of CPython, because those binaries will only access the stable
ABI that will not change when CPython does. Victor Stinner has been
working on better
definition for the
API; as part of that work, he suggested that some of the C extensions in the
standard
library start using it in an effort for CPython to 'eat its
own dog food'. The resulting discussion showed that there is still a fair
amount of confusion about this API—and the thrust of Stinner's overall plan.