Graded assignment Week 3 - There was a problem compiling the code from your notebook

Details:
‘NoneType’ object is not iterable

I have got this output in every exercise of this assignment. I have already tried proposed solutions at the forum like checking metadata, refreshing workspace but the error is still the same and I am getting 0/120 points.

Maybe someone could take a look on notebook?

Please click my name and message your notebook as an attachment.

Hi, I have managed to solve it - I left the last task unsolved which resulted in not checking all the previous ones and compilation error.

@Yinan_Shen
You have not completed all the exercises. Please use #grade-up-to-here comment in your notebook to score the partially completed assignment.