+) Very well done! You have passed all the tests.
-) When you report a fatal error, it is better to give the line number at
the same time
+) Coding is very clear and well structured.
+) You have handled the execution loop very nicely by having a “keepRunning”
variable in the programState class.
+) Good you have proper comments to give enough information about the
+) Naming of classes, methods and variables is good.
+) Good you have all fields private.
+) Nice quality of coding.