This is the 9th post in the Exercises in Programming Style focus series. In the post from two weeks ago, we solved the problem using Object-Oriented Programming: we modeled the problem space using objects. For an object to communicate with another one, a dispatch() method was made available. Remember before the web was ubiquitous? Graphical user interfaces were already a thing. One great and widespread way to handle user interactions is Event-Driven Programming: this has been popularized as the