They run in to async, but do they run in to the internals of how that code is executed?

The chapter that example is from includes the disclaimer:

> In this section, we'll cover the underlying structure of how Futures and asynchronous tasks are scheduled. If you're only interested in learning how to write higher-level code that uses existing Future types and aren't interested in the details of how Future types work, you can skip ahead to the async/await chapter.