code: def apply_node_func(self, nodes):
      iou = nodes.data["iou"] + self.b_iou
      i, o, u = th.chunk(iou, 3, 1)
      i, o, u = th.sigmoid(i), th.sigmoid(o), th.tanh(u)
      c = i * u + nodes.data["c"]
      h = o * th.tanh(c)
      return {"h": h, "c": c}
  
imports: import itertools
  import time
  import dgl
  import networkx
  import numpy
  import torch
  import torch.nn
  import torch.nn.functional
label_desc: Use image node_id 4 for calling the TreeLSTMCell obj's underlying member method code with example usage: obj.apply_node_func(nodes) and returns: dict