[docs] [issue28805] Add documentation for METH_FASTCALL

Serhiy Storchaka added the comment:

Ah? Can you please elaborate your secret plan? :-)

I already said about this. Move the part of parsing keyword argument outside of the function. The caller should unpack keyword arguments and pass just a raw array of PyObject*. Missed arguments are set to NULL. This could make _PyArg_ParseStack() simpler and might even allow to inline arguments parsing code. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue28805> _______________________________________