This code did not work for Python 2.x becaus I was not
importing from future. While I was altering all the files
I updated the header to include license information.
All these changes are to make the book easier to run from
cloud.sagemath.org. You can share individual notebooks there,
but not entire projects.By putting everything under code at the
user only needs to grab that one directory.
More on sagemath later, if I decide to pursue that as a delivery
mechanism...