}
  }

  @Override
  public int inDegree(N node) {
    return isDirected() ? inEdges(node).size() : degree(node);
  }

  @Override
  public int outDegree(N node) {
    return isDirected() ? outEdges(node).size() : degree(node);
  }

  @Override
  public Set<E> adjacentEdges(E edge) {