deleteNodes :: [NodeId] -> StGNG a ()
deleteNodes nids = do
    gng <- State.get
    State.modify (&nodes .~ foldr' Map.delete (gng^.nodes) nids)
deleteNodes :: [NodeId] -> StGNG a ()
deleteNodes nids = do
    gng <- State.get
    State.modify (&nodes .~ foldr' Map.delete (gng^.nodes) nids)
deleteNodes nids = do
    gng <- State.get
    State.modify (&nodes .~ foldr' Map.delete (gng^.nodes) nids)