I think the way sidebar is identified is pretty confusing and requires a lot of knowledge about identify.
It would be a lot more clear if it was as simple as:

```js
const Sidebar = Class({
  // ...
  setup: function(options) { 
    // ...
    model.id = options.id || uuid()
    // ...
  }
  // ....
});

identify.define(Sidebar, sidebar => sidebar.id)
```