Error: 'dot' is not recognized as an internal or external command, operable program or batch file

Context:

Run spp_test.py example from pyCPA in Windows

Solution: Install graphviz
"Graphviz is a package of open-source tools initiated by AT&T Labs Research for drawing graphs specified in DOT language scripts. "

Download graphviz from: https://graphviz.gitlab.io/_pages/Download/Download_windows.html

Remember to add the path to "dot.exe" to the Path environment variable of Windows,
path example: "C:\Program Files (x86)\Graphviz2.38\bin"

After adding path, open cmd.exe again to test if "dot.exe" works.

C:\Users\Username>dot -V
dot - graphviz version 2.38.0 (20140413.2041)  

DONE.