public function serialize()
    {
        $text = array();
        foreach ($this->parameters as $k => $v) {
            $text[] = $k . ': ' . $v;
        }
        foreach ($this->variables as $k => $v) {
            $text[] = 'Set: ' . $k . '=' . $v;
        }
        return implode("\n", $text);
    }