code: def _percolate_up(self, idx, val):
      idx //= 2
      while idx > 0:
          self.values[idx] = self.op(
              self.values[2 * idx], self.values[2 * idx + 1]
          )
          idx //= 2
  
file_path: dynet/examples/reinforcement-learning/reduce_tree.py
imports: import operator
  import numpy
label_desc: Use image node_id 5 for calling the ReduceTree obj's underlying member method code with example usage: obj._percolate_up(idx, val) without return types