Stricter mypy checks

You can enable optional checks to make mypy stricter than it is by default. Here is a small selection:¹

• enable_error_code = ["ignore-without-code"]: no blanket # type: ignore without error code – to avoid silencing unexpected errors and communicating why the type ignore is necessary
• warn_unused_ignores: no unnecessary type ignores
• disallow_untyped_defs: no function definitions without proper annotations
• disallow_any_generics: no generic types without explicit type arguments, for example, list[str] instead of list
• warn_return_any: no Any return in a function that is annotated to return a non-Any type
• warn_unreachable: no unreachable code
• warn_redundant_casts: no redundant type casts

I expect that some of these will become defaults in the future, at least I would like that.