Hi Raymond,

I don't like having the converters in the C implementation too, that's why I'm working on issue28933 to clean this.

> letting the C function handle both -1 and None in the implementation rather than in AC?

It works, yes. But I prefer to clearly split responsibilities: AC being responsible of adapting argument from PyObjects to C types, and C functions being responsible of ... doing their job.

If the idea in issue28933 is accepted, we'll be able to declare hi as simply as:

    hi: Py_ssize_t(c_default="-1") = None

meaning "C function will get a Py_ssize_t, default value for C code is -1, None is documented, and None can be passed to get the C default value", that's this last point "None can be passed to get the C default value" that I introduce in issue28933.

With this syntax, both C converters and the python hi_parameter_converter can be dropped.