The examples in this chapter will use the System.Linq, System.Collections, and System.Collections.Generic namespaces. Therefore, you should add the following using directives to your code if they are not present:
using System.Linq; using System.Collections; using System.Collections.Generic;
In addition to these namespaces, if you download the companion code, you will see that I have also added a using directive for the System.Diagnostics namespace. This will not be necessary if you are typing in the examples from this chapter. It is necessary in the companion code due to some housekeeping code.