public function render()
    {
        if (empty($this->_rows) || empty($this->_columns)) {
            return;
        }

        $stream = $this->getRtf()->getWriter();
        $stream->write('\pard');

        foreach ($this->_rows as $row) {
            $this->renderRowDefinition($row);
            $stream->write("\r\n");
            $this->renderRowCells($row);
            $stream->write("\r\n" . '\row' . "\r\n");
        }

        $stream->write('\pard\itap0' . "\r\n");
    }