Inheritance: extends RecordCollection
 /**
  * @param \Iterator $records
  * @param int $count
  * @param RecordCollection $previousCollection
  */
 public function __construct(\Iterator $records, $count, RecordCollection $previousCollection, Mapping $mapping)
 {
     parent::__construct($records, $previousCollection, $mapping);
     $this->setCount($count);
 }