code: def _propagate(self, index, value):
      parent = (index - 1) // 2
      left, right = 2 * parent + 1, 2 * parent + 2
  
      self.sum_tree[parent] = self.sum_tree[left] + self.sum_tree[right]
  
      if parent != 0:
          self._propagate(parent, value)
  
file_path: SerpentAI/serpent/machine_learning/reinforcement_learning/rainbow_dqn/segment_tree.py
label_desc: Use image node_id 8 for calling the SegmentTree obj's underlying member method code with example usage: obj._propagate(index, value) without return types