I have added a new script (for a better long term maintenance), which create an Exception class that is raised if no Gnuplot installation is detected, and a method that raise that exception if no Gnuplot installation is detected in posix os, which is called in the moment the gp class is called, giving a descritping error message.
install is now install.sh (for avoiding missinderstandings) and now it has a shebang compatible with even BSDs.
Changed print("string" + result) to print(f"string {result}") for better readibility and betterlong term maintenance.
Change for loop in PyGnuplot test to list comprehension in order to improve performance.
I appreciate your attention.