Examples PDFs generated by this script are in /examples subdir. Enjoy :-)
$ python3 -m venv venv
$ source venv/bin/activate
(venv) $ pip3 install -r requirements.txt
(venv) $ python3 visuallearning.py
(venv) $ evince visuallearning.pdf # to view output PDF generated file
$ python3 -m venv venv
$ source venv/bin/activate
(venv) $ pip3 install -r requirements-dev.txt
(venv) $ make tests