code: def reset_stats(self):
          
          scores = list(itertools.chain.from_iterable([v.total_scores for v in self._runners]))
          for v in self._runners:
              v.total_scores.clear()
  
          try:
              return np.mean(scores), np.max(scores)
          except Exception:
              logger.exception("Cannot compute total scores in EnvRunner.")
              return None, None
docs: Returns:
              mean, max: two stats of the runners, to be added to backend