asDescendingArcs :: SizeChangeGraph a b -> Bool
hasDescendingArcs (f, arcs, g) = not (null $ descendingArcs arcs)

hasDescendingArcs :: SizeChangeGraph a b -> Bool
hasDescendingArcs (f, arcs, g) = not (null $ descendingArcs arcs)
hasDescendingArcs (f, arcs, g) = not (null $ descendingArcs arcs)