Hey @jamesob thanks for bringing attention to this function since I do agree it needs some adjustment. However, I'm not sure I'd quite call it a unit test. This function is what I used to design the network - aka deciding how many hidden nodes gives the best result. This is not part of the actual system but is essentially pre-processing done before setting up the system. I think I will pull out this functionality into a separate module and try to be clearer about it being pre-processing. Does that sound reasonable? Thanks!