This presents an entire set as a quiz. to be done:
(1) The answer presentation has to be filled in.
(2) Changes to PG.pl and the environment variables have to be made so that different
answers don't collide. The idea is to prefix all answers with something indicating the
problem number e.g. pRoBlEm04-AnSwEr05 I think it better to pass in an explicit
variable rather than rely on problem numbers.
(3) should this work automatically for NAMED_ANS as well? Pro: --it's done for you.
Con: You can't refer to answers in other parts of the quiz. (Put perhaps you
shouldn't to promote atomic behavior.)