Petrovich::firstname

public function firstname($firstname, $case = Petrovich::CASE_NOMENATIVE) {
//		if(empty($firstname))
//			throw new Exception('Firstname cannot be empty.');

	if ($case === Petrovich::CASE_NOMENATIVE) {
		return $firstname;
	}

	return $this->inflect($firstname,$case,__FUNCTION__);
}