code: def _reset(self, indices):
      
  
      # Pre-conditions: common_preconditions, see `assert_common_preconditions`.
      self.assert_common_preconditions()
  
      # This returns a numpy array with first dimension `len(indices)` and the
      # rest being the dimensionality of the observation.
      return np.stack([self._envs[index].reset() for index in indices])
docs: Resets environments at indices shouldn't pre-process or record.
  
      Subclasses should override this to do the actual reset if something other
      than the default implementation is desired.
  
      Args:
        indices: list of indices of underlying envs to call reset on.
  
      Returns:
        np.ndarray of stacked observations from the reset-ed envs.