 		}
 		
 		/**
-		 * requestHierarchyFromSource
 		 * This function must be implemented by classes by extend AbstractDataSource.
 		 * This function should make a request to the source to fill in the hierarchy at the given subtree.
 		 * This function will only be called once per subtreeNode.

		public const url:LinkableString = newLinkableChild(this, LinkableString);

		/**
		 * getAttributeHierarchy
		 * @return An AttributeHierarchy object that will be updated when new pieces of the hierarchy are filled in.
		 */
		public function get attributeHierarchy():IAttributeHierarchy

		}

		/**
		 * This function will call requestColumnFromSource() if the hierarchyPointer in the column is now valid.
		 * Otherwise, it will call delayColumnRequest() again.
		 * This function may be overridden by classes that extend AbstractDataSource.
