crodas\TextRank\DefaultEvents::filter_keywords PHP Method

    public function filter_keywords(array $keywords)
    {
        return array_filter($keywords, function ($keyword) {
            if (is_numeric($keyword)) {
                return false;
            }
            if ($keyword[0] == mb_strtoupper($keyword[0])) {
                return true;
            }
            return mb_strlen($keyword) > 3;
        });
    }

 public function filter_keywords(array $keywords)
 {
     $keywords = parent::filter_keywords($keywords);
     $tagger = __NAMESPACE__ . '\\POS\\' . ucfirst($this->lang) . '\\Tagger';
     if (class_exists($tagger)) {
         $keywords = $tagger::get($keywords);
     }
     $keywords = array_filter($keywords, function ($word) {
         $word = mb_strtolower($word);
         return empty($this->stopword[$word]);
     });
     return $keywords;
 }