This is not so much a practical, as some extra materials for you to work through if you'd like, showing how 
aspects of documentation and testing work. 
- docs.py
- This is a documented python file, with instructions for how to run file so you can 
see the documentation at the Python prompt. See the comments at the top of the file.
- doctest.py
- This is the same file, but including a doctest. Again, see instructions added as comments.
- Sphinx instructions
- These are instructions for running the Sphinx documentation system over the docs.py file above. Sphinx 
comes as part of Anaconda. 
- Unit test for docs.py
- This is a Unit Test for the docs.py file. Again, instructions in the comments.