NetworkBuilder.directed().allowsSelfLoops(true).expectedNodeCount(16);

  private static final ImmutableNetwork<String, String> IMMUTABLE_NETWORK_A =
      NetworkBuilder.directed().<String, String>immutable().addNode("A").build();
  private static final ImmutableNetwork<String, String> IMMUTABLE_NETWORK_B =
      NetworkBuilder.directed().<String, String>immutable().addNode("B").build();

      NetworkBuilder.directed().allowsSelfLoops(true).expectedNodeCount(16);

  private static final ImmutableNetwork<String, String> IMMUTABLE_NETWORK_A =
      NetworkBuilder.directed().<String, String>immutable().addNode("A").build();
  private static final ImmutableNetwork<String, String> IMMUTABLE_NETWORK_B =
      NetworkBuilder.directed().<String, String>immutable().addNode("B").build();

 * ImmutableNetwork}.
 *
 * <p>You can create an immutable copy of an existing {@code Network} using {@link
 * ImmutableNetwork#copyOf(Network)}:
 *
 * <pre>{@code
 * ImmutableNetwork<Integer, MyEdge> immutableGraph = ImmutableNetwork.copyOf(network);
 * }</pre>
 *
 * <p>Instances of {@link ImmutableNetwork} do not implement {@link MutableNetwork} (obviously!) and

 * ImmutableNetwork}.
 *
 * <p>You can create an immutable copy of an existing {@code Network} using {@link
 * ImmutableNetwork#copyOf(Network)}:
 *
 * <pre>{@code
 * ImmutableNetwork<Integer, MyEdge> immutableGraph = ImmutableNetwork.copyOf(network);
 * }</pre>
 *
 * <p>Instances of {@link ImmutableNetwork} do not implement {@link MutableNetwork} (obviously!) and