gistfile1.txt

>>> from enum import Flag, auto
>>> class Thing(Flag):
...     left = auto()
...     right = auto()
...     middle = left | right
...
>>> Thing.middle
<Thing.middle: 3>
>>> Thing(3)
<Thing.middle: 3>
>>> Thing(2)
<Thing.right: 2>
>>> Thing(1)
<Thing.left: 1>
>>> Thing(0)
<Thing.0: 0>
>>> Thing(-1)
<Thing.middle: 3>
>>> Thing(-2)
<Thing.right: 2>
>>> Thing.left | Thing.right
<Thing.middle: 3>