code: def get_transition(self, frame_idx, env_idx):
          
          past_frame, future_frame = self.get_frame_with_future(frame_idx, env_idx)
  
          data_dict = {
              'observations': past_frame,
              'observations_next': future_frame,
              'actions': self.action_buffer[frame_idx, env_idx],
              'rewards': self.reward_buffer[frame_idx, env_idx],
              'dones': self.dones_buffer[frame_idx, env_idx],
          }
  
          for name in self.extra_data:
              data_dict[name] = self.extra_data[name][frame_idx, env_idx]
  
          return data_dict
docs: Single transition with given index