Issue in Deep Learning Specialization Course 5-Week 3 Assignment

Hello @Hamid_Ali_Khan!

First, you posted this in the General Discussion category but it belongs to DLS. Please correct it as described here. Second, in your title, you said course 5 but in your text, you said course 4. Correct that too.

Regarding your error, so, what is in cell 21? On which code does cell 21 depend? Have you replaced all the None with your code? Or have you deleted/edited any of the pre-written code?