@Override
      public ElementOrder<N> incidentEdgeOrder() {
        return AbstractValueGraph.this.incidentEdgeOrder();
      }

      @Override
      public Set<N> adjacentNodes(N node) {
        return AbstractValueGraph.this.adjacentNodes(node);
      }

      @Override
      public Set<N> predecessors(N node) {
        return AbstractValueGraph.this.predecessors(node);
      }

      @Override

    N nodeV = requireNonNull(nodeConnections.get(nodeU)).adjacentNode(edge);
    return EndpointPair.of(this, nodeU, nodeV);
  }

  @Override
  public Set<N> adjacentNodes(N node) {
    return nodeInvalidatableSet(checkedConnections(node).adjacentNodes(), node);
  }

  @Override
  public Set<E> edgesConnecting(N nodeU, N nodeV) {

    N nodeV = requireNonNull(nodeConnections.get(nodeU)).adjacentNode(edge);
    return EndpointPair.of(this, nodeU, nodeV);
  }

  @Override
  public Set<N> adjacentNodes(N node) {
    return nodeInvalidatableSet(checkedConnections(node).adjacentNodes(), node);
  }

  @Override
  public Set<E> edgesConnecting(N nodeU, N nodeV) {

   */
  @Override
  Set<N> adjacentNodes(N node);

  /**
   * Returns a live view of all nodes in this graph adjacent to {@code node} which can be reached by
   * traversing {@code node}'s incoming edges <i>against</i> the direction (if any) of the edge.
   *
   * <p>In an undirected graph, this is equivalent to {@link #adjacentNodes(Object)}.
   *

   */
  @Override
  Set<N> adjacentNodes(N node);

  /**
   * Returns a live view of all nodes in this graph adjacent to {@code node} which can be reached by
   * traversing {@code node}'s incoming edges <i>against</i> the direction (if any) of the edge.
   *
   * <p>In an undirected graph, this is equivalent to {@link #adjacentNodes(Object)}.
   *

 * in a {@link Network}.
 *
 * @author James Sexton
 * @param <N> Node parameter type
 * @param <E> Edge parameter type
 */
interface NetworkConnections<N, E> {

  Set<N> adjacentNodes();

  Set<N> predecessors();

  Set<N> successors();

  Set<E> incidentEdges();

  Set<E> inEdges();

  Set<E> outEdges();

  /**

   * collections of the following methods:
   *
   * <ul>
   *   <li>For {@link Graph} and {@link ValueGraph}:
   *       <ul>
   *         <li>{@code edges()}: Stable order
   *         <li>{@code adjacentNodes(node)}: Connecting edge insertion order
   *         <li>{@code predecessors(node)}: Connecting edge insertion order
   *         <li>{@code successors(node)}: Connecting edge insertion order

   * collections of the following methods:
   *
   * <ul>
   *   <li>For {@link Graph} and {@link ValueGraph}:
   *       <ul>
   *         <li>{@code edges()}: Stable order
   *         <li>{@code adjacentNodes(node)}: Connecting edge insertion order
   *         <li>{@code predecessors(node)}: Connecting edge insertion order
   *         <li>{@code successors(node)}: Connecting edge insertion order

      }

      @Override
      public boolean allowsSelfLoops() {
        return AbstractNetwork.this.allowsSelfLoops();
      }

      @Override
      public Set<N> adjacentNodes(N node) {
        return AbstractNetwork.this.adjacentNodes(node);
      }

      @Override
      public Set<N> predecessors(N node) {
        return AbstractNetwork.this.predecessors(node);
      }

      @Override

      }

      @Override
      public boolean allowsSelfLoops() {
        return AbstractNetwork.this.allowsSelfLoops();
      }

      @Override
      public Set<N> adjacentNodes(N node) {
        return AbstractNetwork.this.adjacentNodes(node);
      }

      @Override
      public Set<N> predecessors(N node) {
        return AbstractNetwork.this.predecessors(node);
      }

      @Override