public function summarize(array $wordTokens, array $sentenceTokens) : array
    {
        $tokenCounts = array_count_values($wordTokens);
        $scoreKeepers = [];
        for($index = 0; $index < count($sentenceTokens); $index++)
        {
            $scoreKeepers[] = new ScoreKeeper($sentenceTokens[$index], $index);
        }
                       
        foreach($tokenCounts as $token => $freq)
        {
            foreach($scoreKeepers as $sentenceKeeper)
            {
                if(strpos($sentenceKeeper->getToken(), $token) !== false) {
                    
                    $sentenceKeeper->addToScore($freq);
                }
            }
        } 
        
        usort($scoreKeepers, 'score_keeper_sort');
        return $scoreKeepers;
    }