I don't think you posted enough info to solve this problem, but that error means that somewhere in the code there is something called identity_trans and that somewhere in the code you are trying to access an attribute of that object that is not an attribute of that object.

I would look for identity_trans in the code and see where it's trying to reference dataspace_is_numerical as a start.

You posted some of your code but you need to show the part of the code that has dataspace_is_numerical in it for us to really help you.