public function start_template(Smarty_Internal_Template $template, $mode = null)
    {
        if (isset($mode)) {
            $this->index ++;
            $this->offset ++;
            $this->template_data[$this->index] = null;
        }
        $key = $this->get_key($template);
        $this->template_data[$this->index][$key]['start_template_time'] = microtime(true);
    }