Typing on child class' methods of a Generic base class

[Dieter Maurer]

Nicolas Haller wrote at 2022-3-9 10:53 -0500:
> ...
>The documentation about "user-defined generic types"[1] says that I can
>fix some types on a child class (class MyDict(Mapping[str, T]):) but
>doesn't say much about the signature of the methods I need to
>implement/override on that child class.

I have the fealing that this is a case of (generic type) "specialization".
In this setup, `Mapping` would be a generic type with two type
variables `K` (the key type) and `V` (the value type).
The signatures of its methods would use those type variables.
In your example, you specialize the key type to `str` (and
leave the value type generic). The signatures of the methods
would automatically follow this specialization -- without the need
to do anything.