PEP 802: Add Reference Implementation, expand Rejected Ideas

[AA-Turner]

• Change is either:
  • To a Draft PEP
  • To an Accepted or Final PEP, with Steering Council approval
  • To fix an editorial issue (markup, typo, link, header, etc)
• PR title prefixed with PEP number (e.g. PEP 123: Summary of changes)

Added the reference implementation, expanded and added some rejected ideas, added a brief note to backwards compatibility.

A

---

📚 Documentation preview 📚: https://pep-previews--4537.org.readthedocs.build/