If this won't be referenced as a private internally, you could just removed the _isCollectionItem property. It's only available within this code, and this code knows it's a collection item. Also, you could just add this to the prototype of the class in a declaration as...

```
instanceProperties:{
   isCollectionItem:true
}
```

In this way, a statement won't be executed on every instantiation of the class. Not a big deal... just FYI. the instanceProperties declaration is a property of the features declaration block, just like the alphastructor and others.