code: def update_priorities(self, idxes, priorities):
          
          assert len(idxes) == len(priorities)
          for idx, priority in zip(idxes, priorities):
              assert priority > 0
              assert 0 <= idx < len(self._storage)
              self._it_sum[idx] = priority ** self._alpha
              self._it_min[idx] = priority ** self._alpha
  
              self._max_priority = max(self._max_priority, priority)
docs: Update priorities of sampled transitions.
  
          sets priority of transition at index idxes[i] in buffer
          to priorities[i].
  
          Parameters
          ----------
          idxes: [int]
              List of idxes of sampled transitions
          priorities: [float]
              List of updated priorities corresponding to
              transitions at the sampled idxes denoted by
              variable `idxes`.