Tuples are a really useful trick to have up your sleeve when you're working with two linked data points, for example, the first name and the last name or some other piece of information about a person. I like the example that we used int his chapter because, to me, sum and average are two important characteristics of a set of data. That's the basics of tuples covered; we'll take a more detailed look at them in the final chapter of the book. First, though, let's switch to looking at local functions, and see what's new for them in C# 7.
