How to support annotations for a custom type in a C extension?

[MRAB]

On 2021-09-18 16:10, Serhiy Storchaka wrote:
> 18.09.21 09:40, Marco Sulla пише:
>> Ooook..... I have a question. Why is this code not present in
>> dictobject.c? Where are the dict annotations implemented?
> 
> In dictobject.c.
> 
I just had a look at dictobject.c. It too has a cast to PyCFunction.