/**
  * Constructor
  *
  * @param mixed $model
  * @param array $identifiers
  */
 public function __construct($model, array $identifiers = [])
 {
     parent::__construct($model);
     $this->identifiers = $identifiers;
 }
 /**
  * Constructor
  *
  * @param mixed $model
  * @param array $changes
  */
 public function __construct($model, array $changes = [])
 {
     parent::__construct($model);
     $this->changes = $changes;
 }