_sunder_ methods are reserved for internal Enum use, and if the user tries to use any an exception is raised.

Consequently, the enum34 backport uses __order__ instead of _order_ to specify a definition order for its members.

I would like to do two things:

1) add _order_ to the stdlib version

2) ensure the actual definition order is the same as what is specified
   in _order_

Doesn't namedtuple use _fields (as opposed to _fields_) for a similar purpose? Would Enum using _order be more consistent with that?

It would, but that's not what we did.

Currently we have _name_ and _value_; the backport uses __order__ because I didn't want the stdlib version having a hairball when someone tried to use a 2.7 Enum in 3.4 and it didn't occur to me at the time to just add and ignore _order_.

Done in issue26988.

Issue 26988 reverted.  Need to add shim here.

New changeset 10830e1b2966 by Ethan Furman in branch 'default':
issue26981: add _order_ compatibility shim to enum.Enum
https://hg.python.org/cpython/rev/10830e1b2966

Ethan, in Misc/NEWS it says "compatibility ship"

New changeset bdfd4c8384de by Ethan Furman in branch 'default':
issue26981: fix typo
https://hg.python.org/cpython/rev/bdfd4c8384de

Thanks!