Raymond Hettinger firstname.lastname@example.org added the comment:
This is an implementation detail specific to CPython and subject to change. I'm -1 on documenting it for every function/method and thereby making it part of the language spec. We've lived without this spec for almost twenty years, so I'm inclined to think it is truly unimportant.
It is sufficient to mention just once in the docs that CPython functions/methods sometimes don't take keywords.
---------- nosy: +rhettinger