if (!Objects.equal(o1, o2)) {
        return false;
      }
    }
    return !iterator2.hasNext();
  }

  /**
   * Returns a string representation of {@code iterator}, with the format {@code [e1, e2, ..., en]}.
   * The iterator will be left exhausted: its {@code hasNext()} method will return {@code false}.
   */
  public static String toString(Iterator<?> iterator) {