Suggestion: a type for saying not of a type. E.g.: Not[str].

[guillaume-chevalier]

Suggestion: a type for saying not of a type. E.g.: Not[str].

If it exists already, I couldn't find it in the docs.

[JukkaL]

Such feature does not exist. There's a similar existing proposal in the typing repository: python/typing#599. Perhaps you should continue the discussion there, or if your suggestion is significantly different from the existing proposal, you could create a new issue in the typing repository. We generally discuss new type system features in the typing repository first, at least if they seem sufficiently general-purpose.