In order for the view to react when the model changes, we need to bind event listeners: Backbone has its own event system, so we can tell our view (`this`) to `listenTo` change events on the model and automatically re-render. Defining these sorts of relationships is where you really begin to see the return on breaking up your code this way—All you have to do is `set()` the data, and the view will take care of itself!

`listenToOnce` is used like jQuery's `.one()` method, to bind an event handler that will only run the first time the change occurs. In this case, we use that functionality to make our gallery auto-show itself when the model is loaded.