RusPost::checkTrackNumberFormat

protected function checkTrackNumberFormat($trackNumber)
{
	if(mb_strlen($trackNumber) == 13)
		return preg_match('/^[A-Z]{2}?d{9}?[A-Z]{2}$/i', $trackNumber) == 1;
	elseif(mb_strlen($trackNumber) == 14)
		return preg_match('/^d{14}?$/', $trackNumber) == 1;
	else
		return false;
}