I fully agree here. I am working through Deep Learning for Coders now. I have created several errors as I am implementing chapters, but the coding style of fastai makes in impenetrable to debug. It’s an incredible book and a great library when its working as expected, but the number of times i have run into some variant of `method takes N parameters but M were given` is pretty frustrating. Looking through the stack, these are not patterns that would have been accepted in a code review from me for the same reason you mentioned. Making small changes and debugging are both hampered by the style.