Programming languages include lots of abstractions — many ideas that sit on top of other ideas, allowing us to work at a high level. But there are many cases in it’s important to understand what our code is not doing, or where there are values that represent nothingness, or the absence of something. In this talk, Sandi Metz reminds us that even the things that “seem like nothing” our code are actually important, worth thinking about and understanding. While the talk uses Ruby, the ideas are easily transferred to other object-oriented languages, and are food for thought for any programmer using object-oriented techniques.