* Table#cellSet()} iteration order. However, if {@link #orderRowsBy} or {@link #orderColumnsBy}
   * is called, the views are sorted by the supplied comparators.
   *
   * <p>For empty or single-cell immutable tables, {@link #of()} and {@link #of(Object, Object,
   * Object)} are even more convenient.
   *

 *
 * @author Kevin Bourrillion
 * @since 1.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class Booleans {
  private Booleans() {}

  /** Comparators for {@code Boolean} values. */
  private enum BooleanComparator implements Comparator<Boolean> {
    TRUE_FIRST(1, "Booleans.trueFirst()"),
    FALSE_FIRST(-1, "Booleans.falseFirst()");

    private final int trueValue;

 *
 * @author Kevin Bourrillion
 * @since 1.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class Booleans {
  private Booleans() {}

  /** Comparators for {@code Boolean} values. */
  private enum BooleanComparator implements Comparator<Boolean> {
    TRUE_FIRST(1, "Booleans.trueFirst()"),
    FALSE_FIRST(-1, "Booleans.falseFirst()");

    private final int trueValue;

  Iterator<C> createColumnKeyIterator() {
    return new ColumnKeyIterator();
  }

  private class ColumnKeyIterator extends AbstractIterator<C> {
    // Use the same map type to support TreeMaps with comparators that aren't
    // consistent with equals().
    final Map<C, V> seen = factory.get();
    final Iterator<Map<C, V>> mapIterator = backingMap.values().iterator();

  Iterator<C> createColumnKeyIterator() {
    return new ColumnKeyIterator();
  }

  private class ColumnKeyIterator extends AbstractIterator<C> {
    // Use the same map type to support TreeMaps with comparators that aren't
    // consistent with equals().
    final Map<C, V> seen = factory.get();
    final Iterator<Map<C, V>> mapIterator = backingMap.values().iterator();

  }

  public void testReverseOrder() {
    SortedSet<String> set = ImmutableSortedSet.<String>reverseOrder().add("a", "b", "c").build();
    assertThat(set).containsExactly("c", "b", "a").inOrder();
    assertTrue(Comparators.isInOrder(Arrays.asList("c", "b", "a"), set.comparator()));
  }

  private static final Comparator<Object> TO_STRING =
      new Comparator<Object>() {
        @Override