code: def __init__(self, x_size, h_size):
      super(ChildSumTreeLSTMCell, self).__init__()
      self.W_iou = gluon.nn.Dense(3 * h_size, use_bias=False)
      self.U_iou = gluon.nn.Dense(3 * h_size, use_bias=False)
      self.U_f = gluon.nn.Dense(h_size)
  
imports: import itertools
  import time
  import dgl
  import mxnet
  import networkx
  import numpy
  from mxnet import gluon
label_desc: Use image node_id 1 to create a new ChildSumTreeLSTMCell object from inherited base classes: _TreeLSTMCell with example: obj = ChildSumTreeLSTMCell(x_size, h_size)