* 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)}:

   * 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())

    setDistinctValues(MutableNetwork.class, mutableNetworkA, mutableNetworkB);
    setDistinctValues(NetworkBuilder.class, NETWORK_BUILDER_A, NETWORK_BUILDER_B);
    setDistinctValues(Network.class, IMMUTABLE_NETWORK_A, IMMUTABLE_NETWORK_B);
    setDefault(EndpointPair.class, EndpointPair.ordered("A", "B"));
  }

  @Override
  public void testNulls() throws Exception {
    try {

    network.addEdge(N1, N1, E11);
    network.addEdge(N1, N1, E11_A);
    assertThat(network.edgesConnecting(N1, N1)).containsExactly(E11, E11_A);
  }

  private static class NetworkForTest<N, E> extends AbstractNetwork<N, E> {
    private final Network<N, E> network;

    NetworkForTest(Network<N, E> network) {
      this.network = network;
    }

      MutableNetwork<Integer, Object> network =
          networkBuilder.allowsParallelEdges(true).allowsSelfLoops(true).build();

      assertThat(network.nodes()).isEmpty();
      assertThat(network.edges()).isEmpty();
      AbstractNetworkTest.validateNetwork(network);

      while (network.nodes().size() < NUM_NODES) {
        network.addNode(gen.nextInt(NODE_POOL_SIZE));
      }

    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() {

    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.incidentEdges(N1)).containsExactly(E11);
  }

  @Test
  public void incidentNodes_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.incidentNodes(E11).source()).isEqualTo(N1);
    assertThat(network.incidentNodes(E11).target()).isEqualTo(N1);
  }

      MutableNetwork<Integer, Object> network =
          networkBuilder.allowsParallelEdges(true).allowsSelfLoops(true).build();

      assertThat(network.nodes()).isEmpty();
      assertThat(network.edges()).isEmpty();
      AbstractNetworkTest.validateNetwork(network);

      while (network.nodes().size() < NUM_NODES) {
        network.addNode(gen.nextInt(NODE_POOL_SIZE));
      }

    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() {

    setDistinctValues(MutableNetwork.class, mutableNetworkA, mutableNetworkB);
    setDistinctValues(NetworkBuilder.class, NETWORK_BUILDER_A, NETWORK_BUILDER_B);
    setDistinctValues(Network.class, IMMUTABLE_NETWORK_A, IMMUTABLE_NETWORK_B);
    setDefault(EndpointPair.class, EndpointPair.ordered("A", "B"));
  }

  @Override
  public void testNulls() throws Exception {
    try {