* IllegalArgumentException}.
   */
  boolean allowsSelfLoops();

  /** Returns the order of iteration for the elements of {@link #nodes()}. */
  ElementOrder<N> nodeOrder();

  /** Returns the order of iteration for the elements of {@link #edges()}. */
  ElementOrder<E> edgeOrder();

  //
  // Element-level accessors
  //

  /**

                for (Plugin element : tgt) {
                    Object key = getPluginKey().apply(element);
                    Plugin existing = master.get(key);
                    if (existing != null) {
                        element = mergePlugin(element, existing, sourceDominant, context);

                        master.put(key, element);

                        if (!pending.isEmpty()) {

  final transient E element;

  SingletonImmutableSet(E element) {
    this.element = Preconditions.checkNotNull(element);
  }

  @Override
  public int size() {
    return 1;
  }

  @Override
  public boolean contains(@CheckForNull Object target) {
    return element.equals(target);
  }

  @Override
  public UnmodifiableIterator<E> iterator() {

   * support concurrent multisets whose content may change while the method is running.
   *
   * <p>The serialized output consists of the number of distinct elements, the first element, its
   * count, the second element, its count, and so on.
   */
  static <E extends @Nullable Object> void writeMultiset(
      Multiset<E> multiset, ObjectOutputStream stream) throws IOException {

import org.w3c.dom.Document;
import org.w3c.dom.Element;

public class BlockTableRenderer {
    public void renderTo(Iterable<BlockDoc> blocks, Element parent) {
        Document document = parent.getOwnerDocument();

        // <thead>
        //   <tr>
        //     <td>Block</td>
        //     <td>Description</td>
        //   </tr>
        // </thead>
        Element thead = document.createElement("thead");

                    List<Integer> columnKeys = Lists.newArrayList();
                    for (Object element : elements) {
                      @SuppressWarnings("unchecked")
                      Cell<String, Integer, Character> cell =
                          (Cell<String, Integer, Character>) element;
                      columnKeys.add(cell.getColumnKey());

                    List<Integer> columnKeys = Lists.newArrayList();
                    for (Object element : elements) {
                      @SuppressWarnings("unchecked")
                      Cell<String, Integer, Character> cell =
                          (Cell<String, Integer, Character>) element;
                      columnKeys.add(cell.getColumnKey());

  @Override
  public int count(@CheckForNull Object element) {
    return delegate().count(element);
  }

  @CanIgnoreReturnValue
  @Override
  public int add(@ParametricNullness E element, int occurrences) {
    return delegate().add(element, occurrences);
  }

  @CanIgnoreReturnValue
  @Override
  public int remove(@CheckForNull Object element, int occurrences) {
    return delegate().remove(element, occurrences);

  @Override
  @CheckForNull
  public E lower(E element) {
    return forward.higher(element);
  }

  @Override
  @CheckForNull
  public E floor(E element) {
    return forward.ceiling(element);
  }

  @Override
  @CheckForNull
  public E ceiling(E element) {
    return forward.floor(element);
  }

  @Override
  @CheckForNull
  public E higher(E element) {
    return forward.lower(element);
  }

        }

        Document document = parent.getOwnerDocument();

        Element section = document.createElement("section");
        parent.appendChild(section);

        Element title = document.createElement("title");
        section.appendChild(title);
        title.appendChild(document.createTextNode("Script blocks added by the "));
        Element literal = document.createElement("literal");
        title.appendChild(literal);