cleaning up PSUL and making it easy to do the 20158 switch

I'm not 100% on this but I _think_ that if a class method is meant to be called only by other methods from that same class (i.e. it is an internal class method), the convention is to name it with a leading underscore. So in this case: `def _get_ordered_opened(self)` instead of `def get_ordered_opened(self)`. @guillermo-carrasco, maybe you can tell me if I'm right?
I also don't know if the method I'm discussing here is called only internally or also externally, so it may not apply here, but I figured it was a good thing to bring up.