final Map<E, N> outEdgeMap;

  private int selfLoopCount;

  AbstractDirectedNetworkConnections(Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
    this.inEdgeMap = checkNotNull(inEdgeMap);
    this.outEdgeMap = checkNotNull(outEdgeMap);
    this.selfLoopCount = checkNonNegative(selfLoopCount);
    checkState(selfLoopCount <= inEdgeMap.size() && selfLoopCount <= outEdgeMap.size());
  }

  @Override

 */
final class DirectedNetworkConnections<N, E> extends AbstractDirectedNetworkConnections<N, E> {

  DirectedNetworkConnections(Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
    super(inEdgeMap, outEdgeMap, selfLoopCount);
  }

  static <N, E> DirectedNetworkConnections<N, E> of() {
    return new DirectedNetworkConnections<>(

 */
final class DirectedMultiNetworkConnections<N, E> extends AbstractDirectedNetworkConnections<N, E> {

  private DirectedMultiNetworkConnections(
      Map<E, N> inEdges, Map<E, N> outEdges, int selfLoopCount) {
    super(inEdges, outEdges, selfLoopCount);
  }

  static <N, E> DirectedMultiNetworkConnections<N, E> of() {
    return new DirectedMultiNetworkConnections<>(
        new HashMap<E, N>(INNER_CAPACITY, INNER_LOAD_FACTOR),

      int selfLoopCount = network.edgesConnecting(node, node).size();
      return network.allowsParallelEdges()
          ? DirectedMultiNetworkConnections.ofImmutable(inEdgeMap, outEdgeMap, selfLoopCount)
          : DirectedNetworkConnections.ofImmutable(inEdgeMap, outEdgeMap, selfLoopCount);
    } else {
      Map<E, N> incidentEdgeMap =