hasEdgeLabelE :: Label -> Edge -> GS Bool
hasEdgeLabelE l e = do li <- getEdgeLabelIndex l
                       return $ maybe False (`hasEdgeLabelIndexSE` e) li
hasEdgeLabelE :: Label -> Edge -> GS Bool
hasEdgeLabelE l e = do li <- getEdgeLabelIndex l
                       return $ maybe False (`hasEdgeLabelIndexSE` e) li
hasEdgeLabelE l e = do li <- getEdgeLabelIndex l
                       return $ maybe False (`hasEdgeLabelIndexSE` e) li