You have an old but valuable system that is very complex. It functions perfectly and you do not want to alter it. The system accepts several parameters, performs a simulation and returns an image showing a curve as the simulation result. Your task is to design an extension that preserves the same interface as the old system but on top of the image also can draw the coordinate axes and/or can draw a grid of lines. What design pattern should be applied here? Motivate. Sketch the UML diagram.