crodas\TextRank\DefaultEvents::normalize_keywords PHP Method

    public function normalize_keywords(array $keywords)
    {
        return array_map(function ($keyword) {
            return mb_strtolower($keyword);
        }, $keywords);
    }

 public function normalize_keywords(array $keywords)
 {
     $normalized = parent::normalize_keywords($keywords);
     $callback = "stemword";
     $tagger = __NAMESPACE__ . '\\POS\\' . ucfirst($this->lang) . '\\Tagger';
     if (is_callable($callback)) {
         return array_map(function ($keyword) use($callback) {
             return $callback($keyword, 'french', 'UTF_8');
         }, $normalized);
     }
     return $normalized;
 }