I think not var is both clearer and more idiomatic than var is False (I started to put in suggested edits on them, but gave up after 2). not var handles anything that will cast though bool (rather than being exactly the False object).

Never mind, I take back my comment. These are internal values (not user input) and the values are a tri-state between {True, False, None}. This has been broken from a4f1588 .

Re-ordering all of the tests to check for is None first or switching to an Enum would be "better", but I do not think it is worth the effort.

I have a minor preference for the commit to include a note about the non-idiomatic code.