The current iteration of the loop. More specifically, it’s a dictionary with every column in the excel file, but only has their values for the current iteration.
Yes, it is the column name.
This is a very subtle timing issue that’s hard to get around. Basically it tries to load an image for prime_exp before the “Before routine” code is executed. I think easiest best thing to do is probably to give it a placeholder image that will then be replaced when the “Before routine” code executes.