*
     * @return this {@code Builder} object
     */
    @CanIgnoreReturnValue
    public ImmutableValueGraph.Builder<N, V> addNode(N node) {
      mutableValueGraph.addNode(node);
      return this;
    }

    /**
     * Adds an edge connecting {@code nodeU} to {@code nodeV} if one is not already present, and

   * <p><b>Nodes must be unique</b>, just as {@code Map} keys must be. They must also be non-null.
   *
   * @return {@code true} if the graph was modified as a result of this call
   */
  @CanIgnoreReturnValue
  boolean addNode(N node);

  /**
   * Adds an edge connecting {@code nodeU} to {@code nodeV} if one is not already present, and sets
   * a value for that edge to {@code value} (overwriting the existing value, if any).
   *

    MutableGraph<String> mutableGraph = GraphBuilder.directed().build();
    mutableGraph.addNode("A");
    ImmutableGraph<String> immutableGraph = ImmutableGraph.copyOf(mutableGraph);

    assertThat(immutableGraph).isNotInstanceOf(MutableValueGraph.class);
    assertThat(immutableGraph).isEqualTo(mutableGraph);

    mutableGraph.addNode("B");
    assertThat(immutableGraph).isNotEqualTo(mutableGraph);
  }

  @Test

    MutableGraph<String> mutableGraph = GraphBuilder.directed().build();
    mutableGraph.addNode("A");
    ImmutableGraph<String> immutableGraph = ImmutableGraph.copyOf(mutableGraph);

    assertThat(immutableGraph).isNotInstanceOf(MutableValueGraph.class);
    assertThat(immutableGraph).isEqualTo(mutableGraph);

    mutableGraph.addNode("B");
    assertThat(immutableGraph).isNotEqualTo(mutableGraph);
  }

  @Test

    return GraphBuilder.undirected()
        .allowsSelfLoops(allowsSelfLoops)
        .incidentEdgeOrder(incidentEdgeOrder)
        .build();
  }

  @Override
  final void addNode(Integer n) {
    graphAsMutableGraph.addNode(n);
  }

  @Override
  final void putEdge(Integer n1, Integer n2) {
    graphAsMutableGraph.putEdge(n1, n2);
  }

            .nodeOrder(nodeOrder)
            .edgeOrder(edgeOrder)
            .immutable();

    return networkBuilder.build();
  }

  @Override
  void addNode(Integer n) {
    networkBuilder.addNode(n);
    network = networkBuilder.build();
  }

  @Override
  void addEdge(Integer n1, Integer n2, String e) {
    networkBuilder.addEdge(n1, n2, e);
    network = networkBuilder.build();
  }

    this.backingValueGraph = new StandardMutableValueGraph<>(builder);
  }

  @Override
  BaseGraph<N> delegate() {
    return backingValueGraph;
  }

  @Override
  public boolean addNode(N node) {
    return backingValueGraph.addNode(node);
  }

  @Override
  public boolean putEdge(N nodeU, N nodeV) {
    return backingValueGraph.putEdgeValue(nodeU, nodeV, Presence.EDGE_EXISTS) == null;
  }

  @Override

    mutableNetwork.addNode("A");
    ImmutableNetwork<String, Integer> immutableNetwork = ImmutableNetwork.copyOf(mutableNetwork);

    assertThat(immutableNetwork.asGraph()).isInstanceOf(ImmutableGraph.class);
    assertThat(immutableNetwork).isNotInstanceOf(MutableNetwork.class);
    assertThat(immutableNetwork).isEqualTo(mutableNetwork);

    mutableNetwork.addNode("B");

    return GraphBuilder.undirected()
        .allowsSelfLoops(allowsSelfLoops)
        .incidentEdgeOrder(incidentEdgeOrder)
        .build();
  }

  @Override
  final void addNode(Integer n) {
    graphAsMutableGraph.addNode(n);
  }

  @Override
  final void putEdge(Integer n1, Integer n2) {
    graphAsMutableGraph.putEdge(n1, n2);
  }

    public MetadataGraph(MetadataGraphNode entry) {
        this();

        this.entry = entry;
    }

    public MetadataGraph() {
        nodes = new ArrayList<>(64);
    }

    public void addNode(MetadataGraphNode node) {
        nodes.add(node);
    }

    /**
     * find a node by the GAV (metadata)
     *
     * @param md
     */
    public MetadataGraphNode findNode(MavenArtifactMetadata md) {