graphviz

• https://blog.csdn.net/qq_35603331/article/details/81591949
• https://pypi.org/project/graphviz/
• https://blog.csdn.net/a1368783069/article/details/52067404
• https://graphviz.readthedocs.io/en/stable/manual.html#basic-usage
• http://www.graphviz.org/doc/info/shapes.html