bpo-42991 Add 'demux' function to audioop module by Th4R4 · Pull Request #24286 · python/cpython
Thanks for the PR. Unfortunately, the audioop module is now deprecated following the acceptance of PEP 594, so we will no longer be accepting any bugfixes or improvements for this module.
I hope that this does not dissuade you from contributing to CPython, and I'm sorry it took so long for somebody to take a look at your PR 🙂