Runtime validation in type annotations

Motivation I was trying to understand a pattern I&#x27;ve seen in libraries like FastAPI , pydantic or cyclopts ; where type annotations are used for runtime validation via typing.Annotated . You&#x27;ll also see such examples straight from the Python documentation but without an explicit example in how to implement the validation. Here&#x27;s what I&#x27;ve come up with as a minimal example. Type…