This is the mglearn package used in the book, which you can also find in the
accompanying repository
You don't need this repo, all the code is there:
https://github.com/amueller/introduction_to_ml_with_python
This repository is a stand-alone package in case you really feel like you want to install mglearn into your Python environment, for some reason or another. You can install it by running
pip install mglearn
in your terminal, or by running
!pip install mglearn
in Jupyter Notebook.
In particular, installing this package is a very easy way to add it to your Python search path. Or you can just check out the notebooks from the repository above, and add the path to the mglearn subfolder to your PYTHONPATH environment variable (or set it in your IDE).