mrjoes/flask-admin — pull request #685 by ajalt (2014-11-08 19:59:21+00:00)
Title: Fix incorrect usage of NotImplemented constant

[`NotImplemented`](https://docs.python.org/2/library/constants.html#NotImplemented) is a constant singleton used in rich comparison
overloading. It is not callable, and is not an exception.

[`NotImplementedError`](https://docs.python.org/2/library/exceptions.html#exceptions.NotImplementedError) is a built in exception.