Zoom out far enough and a run stops looking like a sequence of decisions at all -- it looks like a single object, lit up all over, doing something you can't quite name from here. That's the whole thing, running.
Pull in and it separates into pieces. Not the whole run anymore -- one branch of it, one cluster of steps that happen to be near each other because they're working on the same thing. From here you can start to tell which parts are talking to which.
Closer still, and it's not a cluster anymore, it's an exchange: one step handing something to the next, a single signal crossing a single gap. This is the unit the whole system is actually made of, repeated however many times it needs to be.
One step, on its own, mid-decision -- everything around it blurred out because it isn't relevant to this one moment. This is the level where "what did it just do" stops being a system-wide question and becomes a specific, answerable one.
