code: public void computeFixedPoint(DiGraph<N, E> graph, N entry) {
      Set<N> entrySet = new LinkedHashSet<>();
      entrySet.add(entry);
      computeFixedPoint(graph, entrySet);
    }
docs: Compute a fixed point for the given graph, entering from the given node.
  @param graph The graph to traverse.
  @param entry The node to begin traversing from.