[NTG-context] Evaluating a Lua expression at the end

Hi. I am trying to set up a system where I can use Lua to find a total that I can display at the end. For example, if I set a question paper, after each question, I do a \directlua{total = total + 4}, assuming this question has 4 points. At the top of my document, I now want to say "Total points:" and display the value of total. Now, naturally, using \directlua gives me 0, since total is 0 at the beginning. But \latelua didn't seem to be what I am looking for. Could someone please guide me in the right direction? Thanks. Kumar