Is there a use case where someone would be expected to not supply an indicator_type or to supply an invalid indicator_type?
If you visited the URL directly, and mistyped I don't want to send a 500 error email to HQ because of this.

> You're also catching AttributeError which anyone reading this code without having the to_function code up next to it would scratch their head at a bit. Why not just catch Exception?
Isn't it best practice to be as specific as possible with your exceptions? I'm choosing to ignore this comment.