ElementOrder<N> incidentEdgeOrder = ElementOrder.unordered();

  Optional<Integer> expectedNodeCount = Optional.absent();

  /**
   * Creates a new instance with the specified edge directionality.
   *
   * @param directed if true, creates an instance for graphs whose edges are each directed; if
   *     false, creates an instance for graphs whose edges are each undirected.
   */

  ElementOrder<N> incidentEdgeOrder = ElementOrder.unordered();

  Optional<Integer> expectedNodeCount = Optional.absent();

  /**
   * Creates a new instance with the specified edge directionality.
   *
   * @param directed if true, creates an instance for graphs whose edges are each directed; if
   *     false, creates an instance for graphs whose edges are each undirected.
   */

   * with the directionality of this graph.
   */
  protected final void validateEndpoints(EndpointPair<?> endpoints) {
    checkNotNull(endpoints);
    checkArgument(isOrderingCompatible(endpoints), ENDPOINTS_MISMATCH);
  }

  /**
   * Returns {@code true} iff {@code endpoints}' ordering is compatible with the directionality of
   * this graph.
   */

   * with the directionality of this graph.
   */
  protected final void validateEndpoints(EndpointPair<?> endpoints) {
    checkNotNull(endpoints);
    checkArgument(isOrderingCompatible(endpoints), ENDPOINTS_MISMATCH);
  }

  /**
   * Returns {@code true} iff {@code endpoints}' ordering is compatible with the directionality of
   * this graph.
   */

  static final String EDGE_ALREADY_EXISTS = "Edge %s already exists in the graph.";
  static final String ENDPOINTS_MISMATCH =
      "Mismatch: endpoints' ordering is not compatible with directionality of the graph";

  /** Singleton edge value for {@link Graph} implementations backed by {@link ValueGraph}s. */
  enum Presence {
    EDGE_EXISTS
  }

  static final String EDGE_ALREADY_EXISTS = "Edge %s already exists in the graph.";
  static final String ENDPOINTS_MISMATCH =
      "Mismatch: endpoints' ordering is not compatible with directionality of the graph";

  /** Singleton edge value for {@link Graph} implementations backed by {@link ValueGraph}s. */
  enum Presence {
    EDGE_EXISTS
  }

// and N2.
//
// e ( NI ) o -> e ( NI ) o

// getStrongTypeN0 maps character's directional code to strong type as required
// by rule N0.
//
// TODO: have separate type for "strong" directionality.
func (p *bracketPairer) getStrongTypeN0(index int) Class {
	switch p.codesIsolatedRun[index] {
	// in the scope of N0, number types are treated as R
	case EN, AN, AL, R:
		return R
	case L:
		return L

// Today, the only supported operator is "LessThan". This may change in the future,
// for example if "consumed" (as opposed to "available") type signals are added.
// In both cases the directionality of the threshold is implicit to the signal type
// (for a given signal, the decision to evict will be made when crossing the threshold
// from either above or below, never both). There is thus no reason to expose the

 * @since 20.0
 */
@Beta
@DoNotMock
@ElementTypesAreNonnullByDefault
public final class GraphBuilder<N> extends AbstractGraphBuilder<N> {

  /** Creates a new instance with the specified edge directionality. */
  private GraphBuilder(boolean directed) {
    super(directed);
  }

  /** Returns a {@link GraphBuilder} for building directed graphs. */
  public static GraphBuilder<Object> directed() {

 * @since 20.0
 */
@Beta
@ElementTypesAreNonnullByDefault
public final class ValueGraphBuilder<N, V> extends AbstractGraphBuilder<N> {

  /** Creates a new instance with the specified edge directionality. */
  private ValueGraphBuilder(boolean directed) {
    super(directed);
  }

  /** Returns a {@link ValueGraphBuilder} for building directed graphs. */
  public static ValueGraphBuilder<Object, Object> directed() {