NS_NOTYETIMPLEMENTED("sorry"); return NS_ERROR_NOT_IMPLEMENTED;
NS_PRECONDITION(aNode != nsnull, "null ptr"); if (! aNode) return NS_ERROR_NULL_POINTER;  nsCOMPtr<nsIRDFResource> resource = do_QueryInterface(aNode); if (resource && IsURLInHistory(resource)) { return NS_NewSingletonEnumerator(aLabels, kNC_child); } else { return NS_NewEmptyEnumerator(aLabels); }
nsGlobalHistory::ArcLabelsIn(nsIRDFNode* aNode,                             nsISimpleEnumerator** aLabels){  NS_NOTYETIMPLEMENTED("sorry");  return NS_ERROR_NOT_IMPLEMENTED;}