code: def _process_err(self, err=None):
          
          self.stats['errors_received'] += 1
  
          if err == "'Authorization Violation'":
              self._err = ErrAuthorization
          elif err == "'Slow Consumer'":
              self._err = ErrSlowConsumer
          elif err == "'Stale Connection'":
              self._err = ErrStaleConnection
          else:
              self._err = Exception(err)
  
          if self._error_cb is not None:
              self._error_cb(err)
docs: Stores the last received error from the server and dispatches the error callback.