 by adding all the elements from another list at a specified position.
            
            @param items: List of elements to add.
            @param index: Position where the elements should be added.
            @return Returns <code>true</code> if the list was changed as a result of the call; otherwise <code>false</code>.
        */
        public function addItemsAt(items:IList, index:int = 0x7fffffff):Boolean {
            return ArrayUtil.addItemsAt(this._collection, items.toArray(), index);
     