code: public void computeFixedPoint(DiGraph<N, E> graph) {
      Set<N> nodes = new LinkedHashSet<>();
      for (DiGraphNode<N, E> node : graph.getDirectedGraphNodes()) {
        nodes.add(node.getValue());
      }
      computeFixedPoint(graph, nodes);
    }
docs: Compute a fixed point for the given graph.
  @param graph The graph to traverse.