Maybe you have changed something in Cell # 6 which you were not supposed to change. Get a fresh copy of your assignment.
Hello @MrPanda,
That error happens when a variable is called before it is defined. Here, model is that variable. Below is the correct order:
From your screenshot, you have reordered it to 1 → 3 → 2.
Please get a fresh copy as Saif suggested for the correct cells’ types and cells’ ordering, and copy your solutions to the new copy.
Cheers,
Raymond
How can i get a fresh copy? Whenever I’m trying to open that jupyter NB it opens the saved file and not any new file
How can i get a fresh copy? Whenever I’m trying to open that jupyter NB it opens the saved file and not any new file
Thank you, guys
. I actually solved the error by downloading the .ipynb file and editing the sequence as @rmwkwok and @saifkhanengr told and then reuploaded the updated file on practice lab.
Hey @MrPanda,
It is great to hear that you have passed the assignment. If you followed through the steps in the link provided by Saif, there was a step that asked you to rename your current notebook, so the system is able to get you a new one. Note that if the notebook’s name wasn’t changed, then the system will not replace your notebook with a new one because that will essentially erase your exisiting notebook (and existing work) which is very unfavourable. Changing the name allows the system to get you a new copy with the original name, and at the same time, your current notebook was saved with a different name. Two notebooks (one new, one old) with two different names. 
Just for other learners who read this, even though it had worked for @MrPanda which I am happy to hear, there is no need to download, change, and upload. If you need a fresh copy, just follow all the steps provided in Saif’s link or here.
Cheers,
Raymond