Using Mypy in production at Spring

At Spring, we maintain a large Python monorepo with complete Mypy coverage configured under Mypy’s strictest available settings. In short, that means every function signature is annotated and implicit Any conversions are disallowed. Lines-of-code is admittedly a poor measure, but as a rough approximation: our monorepo contains over 300,000 lines of Python, with about half of that constituting our