public function getStopWordsFromLanguage(string $language = 'de'): array
  {
    if (\in_array($language, self::$availableLanguages, true) === false) {
      throw new StopWordsLanguageNotExists('language not supported: ' . $language);
    }

    if (!isset($this->stopWords[$language])) {
      $this->loadLanguageData($language);
    }

    return $this->stopWords[$language];
  }