Here: https://docs.python.org/3/reference/datamodel.html#object.__get__

The __get__ signature is defined as:

object.__get__(self, instance, owner)

But here: https://docs.python.org/3/howto/descriptor.html#descriptor-protocol

It is defined as:

descr.__get__(self, obj, type=None)

It is not clear to me as a reader if all descriptors should have the owner/type argument default to None or if it should be required. If it should default to None, I think all doc examples should follow this expectation to make it clear to someone implementing a descriptor for the first time. As best I can tell, the owner/type is always passed. So perhaps the =None shouldn't be there.

Grepping the CPython code, I see lots of definitions for both required and optional, adding more confusion for me.

If there is a definitive answer, I'm happy to follow through by updating the docs.