def METHOD_NAME(self):
    assert self._start_ts is not None
    assert self._stop_ts is None
    self._stop_ts = monotonic()
    event = StepEvent(self, {'state': 'stop'})
    if self.exception:
        event['exception'] = self.exception
    else:
        event['result'] = self.result
    duration = self.duration
    if duration:
        event['duration'] = duration
    self._notify(event)
    steps.pop(self)