*
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/CollectionHelpersExplained#peekingiterator">{@code
 * PeekingIterator}</a>.
 *
 * @author Mick Killianey
 * @since 2.0
 */
@DoNotMock("Use Iterators.peekingIterator")
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface PeekingIterator<E extends @Nullable Object> extends Iterator<E> {
  /**