Create mock library for documentation purposes

[filipsch]

It becomes a bit hard to understand :)

[machow]

This is now done in the following notebooks

https://github.com/datacamp/protowhat/blob/master/example/example_basic.ipynb

https://github.com/datacamp/protowhat/blob/master/example/example_python.ipynb

@filipsch you may be interested in the second, which shows how to add a python parser to protowhat, including pulling out the text being focused on (using the asttokens package) ;)

[filipsch]

@machow very nice!