Yeah, they’re useful when developing, which is why it’s so frustrating when libraries don’t implement types. I’m developing and I’m trying to use a tool that supposedly fits a use case I have, but the tool didn’t come with instructions so it’s practically useless to me. I could open the tool up and look at its guts to figure it out but are you kidding me no, I’m not going back to the stone age for your tool.

Pydantic offers awesome runtime validation (using Rust).