I would have thought there was some trickery or magic to this, or some sort of hidden Django function/signal to use.
But NOPE! With Python, it's a one line wonder!
# Get all subclasses for class
type.__subclasses__(Subscription) That's it! Best part is there's no special imports to do, "type" is already a built-in, so it's available anywhere at any time.
High 5's all round, fuck yeah!
