Slide 13
Here, the original source code becomes an interface to the execution. In red are shown the values taken on by the variables during the program's execution. The double arrow connects a variable with its value at that point; while the single arrow leads from a value into the variable its being assigned to. This allows programmers to see, in a unified way, their code and the actions it performs when executed. The circular arrows allow the programmer to view the previous or next iteration of the corresponding loop. All the iterations have already executed, the programmer is merely browsing back and forth between them. This allows for easier comparison between various states than is possible with a traditional debugger.