public function parseString($script, array $tokens = [])
    {
        $values = array_values($tokens);

        $tokens = array_map(
            function ($token) {
                return '{{' . strtolower($token) . '}}';
            }, array_keys($tokens)
        );


        $this->script = str_replace($tokens, $values, $script);
        return $this;
    }