@Override
  @CanIgnoreReturnValue
  public boolean addNode(N node) {
    checkNotNull(node, "node");

    if (containsNode(node)) {
      return false;
    }

    addNodeInternal(node);
    return true;
  }

  /**
   * Adds {@code node} to the graph and returns the associated {@link NetworkConnections}.
   *
   * @throws IllegalStateException if {@code node} is already present
   */
  @CanIgnoreReturnValue

  }

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

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

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

  @Override

  }

  @Override
  public int degree(N node) {
    if (isDirected()) {
      return IntMath.saturatedAdd(inEdges(node).size(), outEdges(node).size());
    } else {
      return IntMath.saturatedAdd(incidentEdges(node).size(), edgesConnecting(node, node).size());
    }
  }

  @Override
  public int inDegree(N node) {
    return isDirected() ? inEdges(node).size() : degree(node);
  }

  @Override

    private void processTreeNodes(MetadataGraphVertex parentVertex, MetadataTreeNode node, int depth, int pomOrder)
            throws MetadataResolutionException {
        if (node == null) {
            return;
        }

        MetadataGraphVertex vertex = new MetadataGraphVertex(node.md, versionedVertices, scopedVertices);
        vertices.add(vertex);

     * @param session the {@link Session}, must not be {@code null}
     * @param node the {@link Node} to flatten, must not be {@code null}
     * @param scope an optional {@link PathScope} to filter out dependencies
     * @return the flattened list of node
     * @throws DependencyResolverException
     */
    List<Node> flatten(@Nonnull Session session, @Nonnull Node node, @Nullable PathScope scope)
            throws DependencyResolverException;

  }

  @Override
  public int degree(N node) {
    if (isDirected()) {
      return IntMath.saturatedAdd(inEdges(node).size(), outEdges(node).size());
    } else {
      return IntMath.saturatedAdd(incidentEdges(node).size(), edgesConnecting(node, node).size());
    }
  }

  @Override
  public int inDegree(N node) {
    return isDirected() ? inEdges(node).size() : degree(node);
  }

  @Override

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

      @Override

  }

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

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

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

  @Override

	memTotalMD     = NewGaugeMD(memTotal, "Total memory on the node")
	memUsedMD      = NewGaugeMD(memUsed, "Used memory on the node")
	memUsedPercMD  = NewGaugeMD(memUsedPerc, "Used memory percentage on the node")
	memFreeMD      = NewGaugeMD(memFree, "Free memory on the node")
	memBuffersMD   = NewGaugeMD(memBuffers, "Buffers memory on the node")
	memCacheMD     = NewGaugeMD(memCache, "Cache memory on the node")

  tensorflow::Graph graph TF_GUARDED_BY(mu);

  // Runs shape inference.
  tensorflow::ShapeRefiner refiner TF_GUARDED_BY(mu);

  // Maps from name of an operation to the Node* in 'graph'.
  std::unordered_map<tensorflow::string, tensorflow::Node*> name_map
      TF_GUARDED_BY(mu);

  // The keys of this map are all the active sessions using this graph. Each
  // value records whether the graph has been mutated since the corresponding