public function setSystem($system)
    {
        if (!in_array($system, $this->getSupportedTranliterationSystems())) {
            throw new \InvalidArgumentException(
                sprintf('Transliteration system "%s" is not supported for "%s" language.',
                    $system,
                    $this->getLang()
                )
            );
        }

        $this->system = $system;

        return $this;
    }