Help understanding C1W2 Assignment 1: Failed one unit test

I have filled out the notebook according to the instructions, replacing the None values with those of my own.

I pass the initial matrix and 2/3 of the unit tests. Can’t seem to pass the last one. (1) Am I supposed to be adding my own code apart from changing the predesignated None values (2) I can’t seem to find what the issue is, holding up the last unit test.

If you use the File->Open menu, you can view the file. There you will find the test_row_echelon_form() function.

That will let you study which test your code is failing. It should help you with debugging.