> 2. Mike Bayer (SQL Alchemy author) has requested the ability to derive a
> custom metaclass that turns off the Enums-with-members-are-final
> subclassing restriction (relaxing the rule that members of an enum are
> instances of that enum to "members of an enum are instances of that enum,
> or one of its parent enums", but otherwise keeping the same behaviour as
> the standard enums).
>

Nick, after you read the whole code, please consider whether it's not
already complex enough even without catering to every other need out there.