private static void replaceEdge(LinearBekGraph graph, int up, int down) {
      if (!graph.getDottedEdges().hasEdge(up, down)) {
        GraphEdge edge = LinearGraphUtils.getEdge(graph.getGraph(), up, down);
        assert edge != null : "No edge between " + up + " and " + down;
        graph.getHiddenEdges().createEdge(edge);
        graph.getDottedEdges().createEdge(new GraphEdge(up, down, null, GraphEdgeType.DOTTED));
      }
    }
private static void replaceEdge(LinearBekGraph graph, int up, int down)