[nine_k]

Python type annotations get turned into metadata which other tools may inspect at runtime, but the Python runtime itself does nothing with it. It's just well-structured comments.

In Python basically everything is executable, and so are type annotations.

[throwitaway1123]

Somewhat related: you technically can access some type metadata in TypeScript at runtime using the `emitDecoratorMetadata` and `experimentalDecorators` tsconfig options, along with Microsoft's `reflect-metadata` polyfill package. There was a trend at one point where people were writing database ORMs using decorator metadata (e.g. Typegoose, TypeORM, and MikroORM).

This of course requires your build tool to actually understand the TS type system, which is why it's not supported in tools like esbuild and tsx (which uses esbuild under the hood).