is::onBeforePerformIteration

public function onBeforePerformIteration()
{
	if(\CSaleLocation::isLocationProMigrated())
		throw new Main\SystemException('Already migrated');

	if(!isset($this->data['migrator_data']))
		$this->migrator = new CUpdaterLocationPro();
	else
		$this->migrator = unserialize($this->data['migrator_data'], ['allowed_classes' => false]);
}