Chapter Prose

First draft of the chapter prose, in rst form for now. I'm requesting PR to have someone look at the prose. I've also included an svg diagram, but you'll have to pull the repository to see it. I don't think it's viewable within github...

If you want to pull this, this is the 'chapter' branch from https://github.com/malini/500lines
This is a very dense (wordy?) paragraph. Even something as simple as enumerating each step (First..Next...Then...) within a bullet point might help to break up what is currently a bit difficult to read. This might be a good place for a control flow diagram or similar.