PEP 742: Add Discussions-To; use TypeIs

[JelleZijlstra]

• 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)

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📚 Documentation preview 📚: https://pep-previews--3665.org.readthedocs.build/

[hauntsaninja]

(my reservation with TypeIs is that (x: object) -> TypeIs[str] sound like it implies type(x) is str. Exact type is sometimes a useful thing...)

[JelleZijlstra]

@hauntsaninja if you feel strongly enough about this, please share your opinion on Discourse. I'm open to reconsidering the name if there is community consensus going another way.