code: public function overrideOutputFormat($strOutputFormat = null)
      {
          $strOutputFormat = strval($strOutputFormat);
          if (strlen($strOutputFormat)) {
              $this->strOutputFormat = $strOutputFormat;
          } else {
              unset($this->strOutputFormat);
          }
  
          return $this;
      }
docs: Override the output format of the used view.
  
  @param string|null $strOutputFormat The desired output format.
  
  @return ItemList