code: protected function renderDataCellContent($model, $key, $index)
      {
          if ($this->content === null) {
              return $this->grid->formatter->format($this->getDataCellValue($model, $key, $index), $this->format);
          }
  
          return parent::renderDataCellContent($model, $key, $index);
      }
docs: {@inheritdoc}