 import mx.core.IDataRenderer;
 import mx.core.IDeferredInstance;
 import mx.core.IFactory;
+import mx.core.IVisualItem;
 import mx.core.mx_internal;
 import mx.core.UIComponent;
 import mx.events.CollectionEvent;

        
        if (item === null)
            throw new Error("DataGroup content can not contain null items.");
            
        // Rules for lookup:
        // 1. if itemRendererFunction is defined, call it to get the renderer factory and instantiate it
        // 2. if itemRenderer is defined, instantiate one

            itemRemoved(items[i].oldValue, location + i);               
        }
        
        for (i = length-1; i >= 0; i--)
        {
            itemAdded(items[i].newValue, location);
        }
    }
    
