code: public function track($trackingNumber, $requestOption = 'activity')
      {
          $this->trackingNumber = $trackingNumber;
          $this->requestOption = $requestOption;
  
          return $this->getFormattedResponse();
      }
docs: Get package tracking information.
  
  @param string $trackingNumber The package's tracking number.
  @param string $requestOption Optional processing. For Mail Innovations the only valid options are Last Activity and All activity.
  
  @throws Exception
  
  @return stdClass