owlet.firebase serves to integrate a Firebase database into our re-frame web application. We need to talk to Firebase without dropping into evil JS interop — so you shouldn't use
.set! But more generally, we must preserve the integrity of our application's re-frame data flow.
In the description below, I've tried to be entirely consistent in my use of names; i.e. the scope of any name is this entire document. So when you see
the-db-ref, you can count on those names indicating the same entities when they appear later in the document. Also, "ref" or "reference" refers to an instance of [firebase.database.Reference](https://firebase.google.com/docs/reference/js/firebase.database.Refe