: Sets.union(inEdgeMap.keySet(), outEdgeMap.keySet());
        return Iterators.unmodifiableIterator(incidentEdges.iterator());
      }

      @Override
      public int size() {
        return IntMath.saturatedAdd(inEdgeMap.size(), outEdgeMap.size() - selfLoopCount);
      }

      @Override
      public boolean contains(@CheckForNull Object obj) {
        return inEdgeMap.containsKey(obj) || outEdgeMap.containsKey(obj);
      }

  }

  @Override
  public int degree(N node) {
    if (isDirected()) {
      return IntMath.saturatedAdd(predecessors(node).size(), successors(node).size());
    } else {
      Set<N> neighbors = adjacentNodes(node);
      int selfLoopCount = (allowsSelfLoops() && neighbors.contains(node)) ? 1 : 0;
      return IntMath.saturatedAdd(neighbors.size(), selfLoopCount);
    }
  }

  @Override
  public int inDegree(N node) {

                : Sets.union(inEdgeMap.keySet(), outEdgeMap.keySet());
        return Iterators.unmodifiableIterator(incidentEdges.iterator());
      }

      @Override
      public int size() {
        return IntMath.saturatedAdd(inEdgeMap.size(), outEdgeMap.size() - selfLoopCount);
      }

      @Override
      public boolean contains(@CheckForNull Object obj) {
        return inEdgeMap.containsKey(obj) || outEdgeMap.containsKey(obj);
      }