Your help would be greatly appreciated!

Asking the mentors for help is perfectly fine, as long as you don’t post your source code as part of your question on the public forums.

The point is that UNQ_C2 is a completely generic “tag” that they add in the comments of the code cells so that the grader can find them. There is a UNQ_C2 in every assignment. It doesn’t make sense to copy a UNQ_C2 from a different assignment into your notebook, which seems to be what you have done.

If you deleted a cell, the right thing to do is get a clean copy of the notebook in question and then start over gain. You can “copy/paste” any successfully completed work from the previous version. There is a copy about how to get a fresh copy on the FAQ Thread.

If you have undefined variables, then the question is where are they defined. It either means you have not executed the previous cells that define those variables or the code has not yet been written. In the latter case, you don’t need to import the code from somewhere else: you need to write it according to the instructions they give you in the notebook.