protected function getRow($key, $column_widths)
    {
        $row = [];

        for ($j = 0; $j < $this->column_count; $j++) {
            if (isset($this->data[$j]) && array_key_exists($key, $this->data[$j])) {
                $row[] = $this->pad($this->data[$j][$key], $column_widths[$j]);
            }
        }

        return trim(implode('', $row));
    }