ImmutableSortedSet.Builder<String> builder = ImmutableSortedSet.orderedBy(comparator);
      builder.add(BEFORE_FIRST);
      builder.add(BEFORE_FIRST_2);
      builder.add(elements);
      builder.add(AFTER_LAST);
      builder.add(AFTER_LAST_2);
      return builder
          .build()
          .subSet(BEFORE_FIRST_2, AFTER_LAST_2)
          .asList()
          .subList(1, elements.length + 1);
    }
  }

    int len = sequence.length();
    int first;
    int last;

    for (first = 0; first < len; first++) {
      if (!matches(sequence.charAt(first))) {
        break;
      }
    }
    for (last = len - 1; last > first; last--) {
      if (!matches(sequence.charAt(last))) {
        break;
      }
    }

    return sequence.subSequence(first, last + 1).toString();
  }

  /**

    return Tables.transformValues(original, FIRST_CHARACTER);
  }

  @Override
  protected Map<String, Map<Integer, Character>> makePopulatedMap() {
    Table<Integer, String, String> table = HashBasedTable.create();
    table.put(1, "foo", "apple");
    table.put(1, "bar", "banana");
    table.put(3, "foo", "cat");
    return Tables.transformValues(table, FIRST_CHARACTER).columnMap();
  }

    }
  }

  /**
   * Constructs an {@code ImmutableSortedSet} from the first {@code n} elements of {@code contents}.
   * If {@code k} is the size of the returned {@code ImmutableSortedSet}, then the sorted unique
   * elements are in the first {@code k} positions of {@code contents}, and {@code contents[i] ==
   * null} for {@code k <= i < n}.
   *

   * <p>Example:
   *
   * <pre>{@code
   * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP =
   *     Stream.of("banana", "apple", "carrot", "asparagus", "cherry")
   *         .collect(toImmutableSetMultimap(str -> str.charAt(0), str -> str.substring(1)));
   *
   * // is equivalent to
   *
   * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP =
   *     new ImmutableSetMultimap.Builder<Character, String>()

     *
     * @param first the first entry of the table
     * @param entry the entry being removed from the table
     * @return the new first entry for the table
     */
    @GuardedBy("this")
    @CheckForNull
    E removeFromChain(E first, E entry) {
      int newCount = count;
      E newFirst = entry.getNext();
      for (E e = first; e != entry; e = e.getNext()) {

            for (Plugin plugin : plugins) {
                Object key = plugin.getKey();
                Plugin first = normalized.get(key);
                if (first != null) {
                    plugin = merger.mergePlugin(plugin, first);
                }
                normalized.put(key, plugin);
            }

            if (plugins.size() != normalized.size()) {

  }

  /** Returns {@code true} if the second list is a permutation of the first. */
  private static boolean isPermutation(List<?> first, List<?> second) {
    if (first.size() != second.size()) {
      return false;
    }
    ObjectCountHashMap<?> firstCounts = counts(first);
    ObjectCountHashMap<?> secondCounts = counts(second);
    if (first.size() != second.size()) {
      return false;
    }

  @CollectionSize.Require(ONE)
  public void testSingletonSetFirst() {
    assertEquals(a, sortedSet.first());
  }

  @CollectionSize.Require(ONE)
  public void testSingletonSetLast() {
    assertEquals(a, sortedSet.last());
  }

  @CollectionSize.Require(SEVERAL)
  public void testFirst() {
    assertEquals(a, sortedSet.first());
  }

  @CollectionSize.Require(SEVERAL)
  public void testLast() {

    // We can't retrieve even the known first element:
    try {
      broken.next();
      fail();
    } catch (MyException expected) {
    }
    try {
      broken.next();
      fail();
    } catch (MyException expected) {
    }
  }

  private static Iterator<Integer> newDoubler(int first, final int last) {
    return new AbstractSequentialIterator<Integer>(first) {
      @Override