http://www.eecs.wsu.edu/~schneidj/swan/index.php

https://www.python-course.eu/dictionaries.php

http://www2.lib.uchicago.edu/keith/courses/python/class/5/\#custom

https://www.digitalocean.com/community/tutorials/understanding-class-inheritance-in-python-3

https://www.programiz.com/python-programming/methods/built-in/super