This example is defined in the directory: /home/lbesnard/Polychrony/V4.19/Linux/Examples/usingGraphicalLibrary.
You will find in the following sub-directories examples of the use of the predefined Signal Graphical library
The graphical library is provided in the Polychrony distribution in the file $SignalLib_Graphical/libGraphics.SIG.
Remember that to use a library defining a module call FOO, you must add in the program the directive
use FOO;