No, the grader does not care about the optional sections. That means that at least one of your graded functions was not accepted by the grader. Can you show us the actual grader output that you get? Not just the score, but the details. Click “Show grader output”. Unfortunately it’s not always very helpful, but we at least need to start there.
The other thing to realize as a general matter is that the test cases in the notebook don’t always catch all possible errors. Doing software QA is actually pretty difficult. One particular class of errors that the test cases frequently miss is “hard-coding” values or referencing global variables within your functions, instead of the parameters actually being passed in.
[ValidateApp | INFO] Validating ‘/home/jovyan/work/submitted/courseraLearner/W1A1/Convolution_model_Step_by_Step_v1.ipynb’ [ValidateApp | INFO] Executing notebook with kernel: python3 Tests failed on 1 cell(s)! These tests could be hidden. Please check your submission.
Thanks! Ok, sorry, it’s exactly what I was afraid of: it’s one of those cases in which the grader (for some reason I don’t understand) can’t actually tell you which function failed. Please check your DMs and I’ll ping you about it there.