/**
   * Specifies the expected number of edges in the network.
   *
   * @throws IllegalArgumentException if {@code expectedEdgeCount} is negative
   */
  @CanIgnoreReturnValue
  public NetworkBuilder<N, E> expectedEdgeCount(int expectedEdgeCount) {
    this.expectedEdgeCount = Optional.of(checkNonNegative(expectedEdgeCount));
    return this;
  }

  /**

  public static <N, E> MutableNetwork<N, E> copyOf(Network<N, E> network) {
    MutableNetwork<N, E> copy =
        NetworkBuilder.from(network)
            .expectedNodeCount(network.nodes().size())
            .expectedEdgeCount(network.edges().size())
            .build();
    for (N node : network.nodes()) {
      copy.addNode(node);
    }
    for (E edge : network.edges()) {

  public static <N, E> MutableNetwork<N, E> copyOf(Network<N, E> network) {
    MutableNetwork<N, E> copy =
        NetworkBuilder.from(network)
            .expectedNodeCount(network.nodes().size())
            .expectedEdgeCount(network.edges().size())
            .build();
    for (N node : network.nodes()) {
      copy.addNode(node);
    }
    for (E edge : network.edges()) {