}

  static <N, E> DirectedMultiNetworkConnections<N, E> of() {
    return new DirectedMultiNetworkConnections<>(
        new HashMap<E, N>(INNER_CAPACITY, INNER_LOAD_FACTOR),
        new HashMap<E, N>(INNER_CAPACITY, INNER_LOAD_FACTOR),
        0);
  }

  static <N, E> DirectedMultiNetworkConnections<N, E> ofImmutable(
      Map<E, N> inEdges, Map<E, N> outEdges, int selfLoopCount) {