```
**Diagram 1: Types of Code**

                       high
                       ^                ||
                       ^                ||
                       ^ boring I/O     ||  interesting I/O
                       ^                ||
cost of testing        ^ ================================
                       ^                ||
                       ^                ||
                       ^ boring         ||  interesting
                       ^ transformation ||  transformation
                       ^                ||
                       low >>>>>>>>>>>>>>>>>>>>>>>>>>>>> high
                                benefit of testing

```