code: def _get_upload_session_status(res):
          
          response = json.loads(res.body.decode())
          if 'sessionStatus' not in response:
              try:
                  info = (
                      response['errorMessage']['additionalInfo']
                      ['uploader_service.GoogleRupioAdditionalInfo']
                      ['completionInfo']['customerSpecificInfo']
                  )
                  reason = '{} : {}'.format(info['status'], info['message'])
              except KeyError:
                  reason = 'unknown reason'
              raise exceptions.NetworkError('image upload failed: {}'.format(
                  reason
              ))
          return response['sessionStatus']
docs: Parse the image upload response to obtain status.
  
          Args:
              res: http_utils.FetchResponse instance, the upload response
  
          Returns:
              dict, sessionStatus of the response
  
          Raises:
              hangups.NetworkError: If the upload request failed.