Few basic graph algorithms in Python.
Copyleft lion137.
Read also: http://lion137.blogspot.co.uk/2017/08/new-repository-python-graphs.html
Heap data structure, thanks to Runestone Interactive:
https://interactivepython.org/runestone/default/user/login?_next=/runestone/default/index
Import graph_classes from file graph_classes.py and any needed functions.