code: def failed(self):
          
          try:
              self._validate_parameters()
              self._base_delay = min(
                  self._base_delay * self.exp_fac,
                  self.delay_max)
              self._update_delay()
          except Exception:
              ic_logger.exception(
                  'Unhandled exception trying to calculate a retry timout')
docs: Call whenever an action has failed, grows delay exponentially
  
          After calling failed(), the `delay` property contains the next delay