- | Modify the finite map holding the nodes in the graph.
graphMapModify
        :: (UniqFM (Node k cls color) -> UniqFM (Node k cls color))
        -> Graph k cls color -> Graph k cls color

graphMapModify f graph
        = graph { graphMap      = f (graphMap graph) }

graphMapModify
        :: (UniqFM (Node k cls color) -> UniqFM (Node k cls color))
        -> Graph k cls color -> Graph k cls color
graphMapModify f graph
        = graph { graphMap      = f (graphMap graph) }
graphMapModify f graph
        = graph { graphMap      = f (graphMap graph) }