}

  static <N, E> UndirectedNetworkConnections<N, E> ofImmutable(Map<E, N> incidentEdges) {
    return new UndirectedNetworkConnections<>(ImmutableBiMap.copyOf(incidentEdges));
  }

  @Override
  public Set<N> adjacentNodes() {
    return Collections.unmodifiableSet(((BiMap<E, N>) incidentEdgeMap).values());
  }

  @Override
  public Set<E> edgesConnecting(N node) {

    this.selfLoopCount = checkNonNegative(selfLoopCount);
    checkState(selfLoopCount <= inEdgeMap.size() && selfLoopCount <= outEdgeMap.size());
  }

  @Override
  public Set<N> adjacentNodes() {
    return Sets.union(predecessors(), successors());
  }

  @Override
  public Set<E> incidentEdges() {
    return new AbstractSet<E>() {
      @Override
      public UnmodifiableIterator<E> iterator() {

 * a {@link Graph}.
 *
 * @author James Sexton
 * @param <N> Node parameter type
 * @param <V> Value parameter type
 */
interface GraphConnections<N, V> {

  Set<N> adjacentNodes();

  Set<N> predecessors();

  Set<N> successors();

  /**
   * Returns an iterator over the incident edges.
   *

   */
  Set<N> adjacentNodes(N node);

  /**
   * Returns a live view of all nodes in this network adjacent to {@code node} which can be reached
   * by traversing {@code node}'s incoming edges <i>against</i> the direction (if any) of the edge.
   *
   * <p>In an undirected network, this is equivalent to {@link #adjacentNodes(Object)}.
   *

    newBuilder.nodeOrder = checkNotNull(nodeOrder);
    return newBuilder;
  }

  /**
   * Specifies the order of iteration for the elements of {@link Graph#edges()}, {@link
   * Graph#adjacentNodes(Object)}, {@link Graph#predecessors(Object)}, {@link
   * Graph#successors(Object)} and {@link Graph#incidentEdges(Object)}.
   *
   * <p>The default value is {@link ElementOrder#unordered() unordered} for mutable graphs. For

    newBuilder.nodeOrder = checkNotNull(nodeOrder);
    return newBuilder;
  }

  /**
   * Specifies the order of iteration for the elements of {@link ValueGraph#edges()}, {@link
   * ValueGraph#adjacentNodes(Object)}, {@link ValueGraph#predecessors(Object)}, {@link
   * ValueGraph#successors(Object)} and {@link ValueGraph#incidentEdges(Object)}.
   *

    newBuilder.nodeOrder = checkNotNull(nodeOrder);
    return newBuilder;
  }

  /**
   * Specifies the order of iteration for the elements of {@link ValueGraph#edges()}, {@link
   * ValueGraph#adjacentNodes(Object)}, {@link ValueGraph#predecessors(Object)}, {@link
   * ValueGraph#successors(Object)} and {@link ValueGraph#incidentEdges(Object)}.
   *

        ? DirectedGraphConnections.ofImmutable(
            node, graph.incidentEdges(node), successorNodeToValueFn)
        : UndirectedGraphConnections.ofImmutable(
            Maps.asMap(graph.adjacentNodes(node), successorNodeToValueFn));
  }

  /**
   * A builder for creating {@link ImmutableValueGraph} instances, especially {@code static final}
   * graphs. Example:
   *
   * {@snippet :

    return new DirectedGraphConnections<>(
        adjacentNodeValues,
        orderedNodeConnectionsBuilder.build(),
        predecessorCount,
        successorCount);
  }

  @Override
  public Set<N> adjacentNodes() {
    if (orderedNodeConnections == null) {
      return Collections.unmodifiableSet(adjacentNodeValues.keySet());
    } else {
      return new AbstractSet<N>() {
        @Override

    assertThat(ordered.target()).isEqualTo("target");
    assertThat(ordered.nodeU()).isEqualTo("source");
    assertThat(ordered.nodeV()).isEqualTo("target");
    assertThat(ordered.adjacentNode("source")).isEqualTo("target");
    assertThat(ordered.adjacentNode("target")).isEqualTo("source");
    assertThat(ordered.toString()).isEqualTo("<source -> target>");
  }

  @Test
  public void testUnorderedEndpointPair() {