I'm very interested in this -- however this week the Python Core Dev sprint is eating up all my time. Sometime in the next few weeks I hope to catch up with various typing-sig topics (also the variadics pep).

On Tue, Oct 20, 2020 at 2:50 PM Eric Traut <eric@traut.com> wrote:
As Guido suggested, I've created a new draft PEP for "User-defined Type Guards". Input is welcome.

Draft Proposal (in fork): https://github.com/erictraut/peps/blob/master/pep-9999.rst
Draft Proposal (branch compare): https://github.com/python/peps/compare/master...erictraut:master

Eric Traut
Contributor to Pyright and Pylance
Microsoft Corp.
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