CSC151 2010S, Class 28: Another Image Model: Iterating Over Positions

Overview:
* Iterating over positions.
* Blends and other positionally-computed images.
* Drawing simple shapes.
* Lab.

Admin:
* Reading for Monday: List Recursion, Revisited.
* Yes, that's right, we have another week of recursion.  Fun, right?
* I should have a cool surprise from SIGCSE for you next week.
* Don't forget to email me questions on the exam.  I think I've responded to all the ones that I've received.
* Please don't forget to check the Q&A section at the end of the exam.