/** Constructs a {@link MutableGraph} with the properties specified in {@code builder}. */
  StandardMutableGraph(AbstractGraphBuilder<? super N> builder) {
    this.backingValueGraph = new StandardMutableValueGraph<>(builder);
  }

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

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