I'm not 100% about default=None vs. default=False or default={}. default={} appeals to me as a design point but I'm guessing it requires more expensive mongo interaction? If @cpennington says it's all the same though then I think you should do that. Then you can eliminate the ```if``` below in favor of just using the .get() call, and the expected structure of the variable is always inspectable. But if that's inconvenient with mongo I guess I don't feel very strongly about None vs. False.