Response Type Safety

[aminulacter]

The __call method returns mixed types (ResponseInterface|object|null) which could lead to type safety issues. Should implement stricter return type declarations and better type checking

[hopeseekr]

See Issue #16: Integrate SimpleDTO.

I've been trying to tackle this for 5-6 years now, on and off.

Anyone's contribution is welcome. This might be a good test-case for ASI LLMs...