if (connections.removeSuccessor(node) != null) {
        connections.removePredecessor(node);
        --edgeCount;
      }
    }

    for (N successor : ImmutableList.copyOf(connections.successors())) {
      // requireNonNull is safe because the node is a successor.
      requireNonNull(nodeConnections.getWithoutCaching(successor)).removePredecessor(node);
      requireNonNull(connections.removeSuccessor(successor));

      if (connections.removeSuccessor(node) != null) {
        connections.removePredecessor(node);
        --edgeCount;
      }
    }

    for (N successor : ImmutableList.copyOf(connections.successors())) {
      // requireNonNull is safe because the node is a successor.
      requireNonNull(nodeConnections.getWithoutCaching(successor)).removePredecessor(node);
      requireNonNull(connections.removeSuccessor(successor));

    }
    return (V) value;
  }

  @Override
  public void removePredecessor(N node) {
    checkNotNull(node);

    Object previousValue = adjacentNodeValues.get(node);
    boolean removedPredecessor;

    if (previousValue == PRED) {
      adjacentNodeValues.remove(node);
      removedPredecessor = true;
    } else if (previousValue instanceof PredAndSucc) {

    }
    return (V) value;
  }

  @Override
  public void removePredecessor(N node) {
    checkNotNull(node);

    Object previousValue = adjacentNodeValues.get(node);
    boolean removedPredecessor;

    if (previousValue == PRED) {
      adjacentNodeValues.remove(node);
      removedPredecessor = true;
    } else if (previousValue instanceof PredAndSucc) {