return AbstractValueGraph.this.degree(node);
      }

      @Override
      public int inDegree(N node) {
        return AbstractValueGraph.this.inDegree(node);
      }

      @Override
      public int outDegree(N node) {
        return AbstractValueGraph.this.outDegree(node);
      }
    };
  }

  @Override
  public Optional<V> edgeValue(N nodeU, N nodeV) {

   * all "null" (UNSET).
   *
   * <p>A node with "prev" pointer equal to {@code ENDPOINT} is the first node in the linked list,
   * and a node with "next" pointer equal to {@code ENDPOINT} is the last node.
   */
  @CheckForNull @VisibleForTesting transient long[] links;

  /** Pointer to the first node in the linked list, or {@code ENDPOINT} if there are no entries. */
  private transient int firstEntry;

  }

  @Override
  @CheckForNull
  public V value(N node) {
    return adjacentNodeValues.get(node);
  }

  @Override
  public void removePredecessor(N node) {
    @SuppressWarnings("unused")
    V unused = removeSuccessor(node);
  }

  @Override
  @CheckForNull
  public V removeSuccessor(N node) {
    return adjacentNodeValues.remove(node);
  }

  @Override

  public N removeOutEdge(E edge) {
    N node = super.removeOutEdge(edge);
    Multiset<N> adjacentNodes = getReference(adjacentNodesReference);
    if (adjacentNodes != null) {
      checkState(adjacentNodes.remove(node));
    }
    return node;
  }

  @Override
  public void addInEdge(E edge, N node, boolean isSelfLoop) {
    if (!isSelfLoop) {
      addOutEdge(edge, node);
    }
  }

  @Override

  }

  @Override
  @CheckForNull
  public V value(N node) {
    return adjacentNodeValues.get(node);
  }

  @Override
  public void removePredecessor(N node) {
    @SuppressWarnings("unused")
    V unused = removeSuccessor(node);
  }

  @Override
  @CheckForNull
  public V removeSuccessor(N node) {
    return adjacentNodeValues.remove(node);
  }

  @Override

        NodeList childNodes = element.getChildNodes();
        for (int i = 0; i < childNodes.getLength(); i++) {
            Node node = childNodes.item(i);
            if (node instanceof Element) {
                Element childElement = (Element) node;
                if (childElement.getTagName().equals(childName)) {
                    matches.add(childElement);
                }
            }
        }

    }

    public static def leftShift(Node parent, Closure cl) {
        DomBuilder builder = new DomBuilder(parent)
        cl.delegate = builder
        cl.call()
        return builder.elements[0]
    }

    public static void leftShift(Node parent, Node node) {
        parent.appendChild(parent.ownerDocument.importNode(node, true))
    }

    public static void addFirst(Node parent, Closure cl) {

     * sets a value for that edge to {@code value} (overwriting the existing value, if any).
     *
     * <p>If the graph is directed, the resultant edge will be directed; otherwise, it will be
     * undirected.
     *
     * <p>Values do not have to be unique. However, values must be non-null.
     *

 *
 * @author James Sexton
 * @param <N> Node parameter type
 * @param <E> Edge parameter type
 */
@ElementTypesAreNonnullByDefault
abstract class AbstractDirectedNetworkConnections<N, E> implements NetworkConnections<N, E> {
  /** Keys are edges incoming to the origin node, values are the source node. */
  final Map<E, N> inEdgeMap;

  /** Keys are edges outgoing from the origin node, values are the target node. */

   *         <li>{@code adjacentNodes(node)}: Stable order
   *         <li>{@code predecessors(node)}: Connecting edge insertion order
   *         <li>{@code successors(node)}: Connecting edge insertion order
   *         <li>{@code incidentEdges(node)}: Stable order
   *         <li>{@code inEdges(node)}: Edge insertion order
   *         <li>{@code outEdges(node)}: Edge insertion order
   *         <li>{@code adjacentEdges(edge)}: Stable order