public function getSynonyms($class = null, $words = [])
    {
        // Method One:
        $query = Synonym::find();
        if (is_array($words) && !empty($words)) {
            $query = $query->word($words);
        }
        if (!($class === null || $class === false || (is_string($class) && empty($class)))) {
            $query = $query->extension($class);
        }
        foreach ($query->all() as $synonyms) {
            yield $synonyms;
        }
        // Method Two:
        //return Synonym::find()->all();
    }