I was not implying that the concept of recursion is at all advanced. I was implying that the problems to be solved in the template layer are very simple.

I won't be able to come back to you because it would be too inefficient doing something more advanced than that in the template layer. Because rather than write the python to write template syntax to be interpreted back into python, I simply wrote the logic in one-pass python in the view function. It's more direct, runs faster, and your templates are clearer to designers if you're working in a group project.