We add the ability to map over signals and control subscriptions in a more fine-grained manner. Along the way, we improve the signal ownership model and implement the concept of disposables.
We build upon the Future type of a previous episode to implement a simple reactive library. Along the way, we dive into debugging a reference cycle in our implementation.
We refactor our code by moving the app's flow from the storyboard into a separate class. Our goal is to manage the view controller flow from a central place so that view controllers don't have implicit knowledge of their context.