It looks like the values in AutoNumberEnum are
consecutive integers 1,2,3,...
Have you considered an option (keyword argument) to change
this to powers of two 1,2,4,8,...?
Why would you want that? I remind you that this descends from Enum,
so its members won't be directly interchangeable with ints.
Presumably you want a bitfield enum, and those should descend from
IntEnum.
TBH I'd prefer the AutoNumberEnum *not* have this feature; it's
already a little too magical for my tastes.