modifyNode :: (Node a -> Node a) -> NodeId -> StGNG a ()
modifyNode f nid = State.modify (&nodes %~ Map.adjust f nid)
modifyNode :: (Node a -> Node a) -> NodeId -> StGNG a ()
modifyNode f nid = State.modify (&nodes %~ Map.adjust f nid)
modifyNode f nid = State.modify (&nodes %~ Map.adjust f nid)