Subview shorthands for assigning model and/or collection

```javascript
subviews: {
        user: {
            container: '[role=user]',
            constructor: UserView,
            model: 'model.user' // Will set subview model to model.user and wait for it.
        },
        todos: {
            container: '[role=todos]',
            constructor: TodoView,
            collection: 'model.todos' // Will set subview collection to model.todos and wait for it.
        }
    }
```
Can you explain to me how waitFor works? In this case and others it would be nice is waitFor could be an array.