I’ve reviewed the PEP and the PR, and it all looks good now, so PEP 627 is now formally accepted! Congratulations @encukou and thanks for all the work you put into getting this done 
I’ve added a few review comments to the PR - nothing major, and nothing that affects the acceptance, but if you could take a look that would be good.
Also, if you could update the PEP to note its accepted status, that would be great.