* subtype of {@code Network} that provides methods for adding and removing nodes and edges. If you
 * do not need to mutate a network (e.g. if you write a method than runs a read-only algorithm on
 * the network), you should use the non-mutating {@link Network} interface, or an {@link
 * ImmutableNetwork}.
 *
 * <p>You can create an immutable copy of an existing {@code Network} using {@link
 * ImmutableNetwork#copyOf(Network)}:

    addEdges(network);

    assertThat(network.edgeOrder()).isEqualTo(ElementOrder.insertion());
    assertThat(network.edges()).containsExactly("i", "e", "p").inOrder();
    assertThat(network.nodeOrder()).isEqualTo(ElementOrder.insertion()); // default
  }

  // The default ordering is INSERTION unless otherwise specified.
  @Test
  public void edgeOrder_default() {

  /**
   * Returns a view of {@code network} with the direction (if any) of every edge reversed. All other
   * properties remain intact, and further updates to {@code network} will be reflected in the view.
   */
  public static <N, E> Network<N, E> transpose(Network<N, E> network) {
    if (!network.isDirected()) {
      return network; // the transpose of an undirected network is an identical network
    }

/**
 * A concrete interceptor chain that carries the entire interceptor chain: all application
 * interceptors, the OkHttp core, all network interceptors, and finally the network caller.
 *
 * If the chain is for an application interceptor then [exchange] must be null. Otherwise it is for
 * a network interceptor and [exchange] must be non-null.
 */
class RealInterceptorChain(
  internal val call: RealCall,

  private ImmutableNetwork(Network<N, E> network) {
    super(
        NetworkBuilder.from(network), getNodeConnections(network), getEdgeToReferenceNode(network));
  }

  /** Returns an immutable copy of {@code network}. */
  public static <N, E> ImmutableNetwork<N, E> copyOf(Network<N, E> network) {
    return (network instanceof ImmutableNetwork)
        ? (ImmutableNetwork<N, E>) network

    @Throws(IOException::class)
    fun proceed(request: Request): Response

    /**
     * Returns the connection the request will be executed on. This is only available in the chains
     * of network interceptors. For application interceptors this is always null.
     */
    fun connection(): Connection?

    /**
     * Returns the `Call` to which this chain belongs.
     */
    fun call(): Call

    /**

   * network}.
   *
   * <p>The "queryable" properties are those that are exposed through the {@link Network} interface,
   * such as {@link Network#isDirected()}. Other properties, such as {@link
   * #expectedNodeCount(int)}, are not set in the new builder.
   */
  public static <N, E> NetworkBuilder<N, E> from(Network<N, E> network) {
    return new NetworkBuilder<N, E>(network.isDirected())

    return Maps.asMap(network.edges(), network::incidentNodes);
  }

/**
 * A subinterface of {@link Network} which adds mutation methods. When mutation is not required,
 * users should prefer the {@link Network} interface.
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @param <N> Node parameter type
 * @param <E> Edge parameter type
 * @since 20.0
 */
public interface MutableNetwork<N, E> extends Network<N, E> {

  /**

    return graph.isDirected() ? ordered(nodeU, nodeV) : unordered(nodeU, nodeV);
  }

  /** Returns an {@link EndpointPair} representing the endpoints of an edge in {@code network}. */
  static <N> EndpointPair<N> of(Network<?, ?> network, N nodeU, N nodeV) {
    return network.isDirected() ? ordered(nodeU, nodeV) : unordered(nodeU, nodeV);
  }

  /**
   * If this {@link EndpointPair} {@link #isOrdered()}, returns the node which is the source.