I've never had good luck with trying to import the Unicode literals in Python 2. It usually works better for me to leave that out, usually code still works on both without it. It tends to break libraries.
And, I very much doubt that an introductory computer science book would be covering anything that would be different with old-style classes, much less with the absolute import. For that matter, it might use the new style super, etc; those tend to be more advanced concepts.
To use new style classes: replace class Something: with class Something(object):