public function getLexicon() : array
    {
        if(!file_exists($this->getTxtFilePath())) {
            throw new \RuntimeException('Package vader_lexicon must be installed, php textconsole pta:install:package vader_lexicon');
        }
        
        if(empty($this->lexicon)) {
            $fh = fopen($this->getTxtFilePath(), "r");
            while (($rows[] = fgetcsv($fh, 4096, "\t")) !== FALSE);
            
            fclose($fh);
            
            foreach($rows as $row)
            {
                $this->lexicon[$row[0]] = $row[1];
            }            
        }
        return $this->lexicon;
    }