I also was not able to get this git checkout command to work. I am going to just look at github, I suppose the correct information is stashed away there somewhere. I don't want to run the app, just look at the code to learn how to use piston from within python properly.

never mind, I actually found the piston API documents. They are excellent btw: http://piston.readthedocs.io/en/develop/lib.html