Throughout this book, you will see a lot of diagrams explaining how an operator works. These diagrams are a graphical representation of observables and operations in those observables. Usually, the diagrams consist of three parts. On the top they shows a line with balls representing the initial state of an observable. The line itself represents an observable. The circles are events that happened in this observable and they are pushed from left to right; therefore, the leftmost ball is the first event, the second one is the second, and so on. This is illustrated in the following diagram:
So, the preceding line represents an observable with three emitted events. The string at the center of each circle is the value emitted by that event. The short vertical line on the right-hand side of the diagram represents the end of this observable. This diagram is a graphical representation...
