.addEqualityGroup(stringFunnel(UTF_8))
        .addEqualityGroup(stringFunnel(US_ASCII))
        .addEqualityGroup(
            sequentialFunnel(integerFunnel()),
            SerializableTester.reserialize(sequentialFunnel(integerFunnel())))
        .addEqualityGroup(sequentialFunnel(longFunnel()))
        .testEquals();
  }

  public static <E extends @Nullable Object> Funnel<Iterable<? extends E>> sequentialFunnel(
      Funnel<E> elementFunnel) {
    return new SequentialFunnel<>(elementFunnel);
  }

  private static final class SequentialFunnel<E extends @Nullable Object>
      implements Funnel<Iterable<? extends E>> {
    private final Funnel<E> elementFunnel;

    SequentialFunnel(Funnel<E> elementFunnel) {