The previous title gave the impression that this PEP was about
splitting the standard library into separately versioned pieces,
when it's actually a far more modest proposal to improve the
error messages that users receive when pieces are missing, as
well as to provide a standard library API to retrieve the full
list of expected standard library module names.
It also includes a number of other improvements that came up
during the PR review:
- explicitly limit metadata to top level modules
- be clear that private stdlib modules need to be listed
- provide more details on which modules would be optional
- use tkinter and idlelib as additional examples
- provide rationale for packaging modules being mandatory
- provide example error messages for missing submodules
- add subheadings to the design discussion section
- rename Open Questions to Deferred Ideas to avoid scope
creep in the initial proposal