code: def api_registration_check(self):
          '''
              Reach out to the inventory API to check
              whether a machine exists.
  
              Returns
                  True    system exists in inventory
                  False   system does not exist in inventory
                  None    error connection or parsing response
          '''
          if self.config.legacy_upload:
              return self._legacy_api_registration_check()
  
          logger.debug('Checking registration status...')
          results = self._fetch_system_by_machine_id()
          if not results:
              return results
  
          logger.debug('System found.')
          logger.debug('Machine ID: %s', results[0]['insights_id'])
          logger.debug('Inventory ID: %s', results[0]['id'])
          return Truf api_registration_check(self):
          '''
              Reach out to the inventory API to check
              whether a machine exists.
  
              Returns
                  True    system exists in inventory
                  False   system does not exist in inventory
                  None    error connection or parsing response
          '''
          if self.config.legacy_upload:
              return self._legacy_api_registration_check()
  
          logger.debug('Checking registration status...')
          results = self._fetch_system_by_machine_id()
          if not results:
              return results
  
          logger.debug('System found.')
          logger.debug('Machine ID: %s', results[0]['insights_id'])
          logger.debug('Inventory ID: %s', results[0]['id'])
          return True
docs: Reach out to the inventory API to check
              whether a machine exists.
  
              Returns
                  True    system exists in inventory
                  False   system does not exist in inventory
                  None    error connection or parsing response