[oblvious-earth]

> Python doesn't have a standards document. It has a reference implementation that defines the language.

That's not quite strictly true, Python does have a documented "Language Reference": https://docs.python.org/3/reference/index.html

If there is a contradiction between the Language Reference and CPython then one, or both, of them needs to be updated and it's treated on a case by case basis.

If an alternative Python implementation follows the Language Reference but chooses different details outside it, that doesn't stop it from being "Python". Of course practically speaking most alternative implementations are incentivized to closely follow CPython.

[solarkraft]

And what about PEPs, which describe (in pretty good detail) what changes will be made?

[samus]

They describe large-scale changes that usually also lead to changes of implementation details. But their biggest disadvantage is that they are not kept up to date when things change due to later PEPs or smaller-scale changes interfering. After landing, they are of historical value only.