code: def reduce_func(self, nodes):
      h, c = nodes.mailbox["h"], nodes.mailbox["c"]
      iou, c = self._reduce_func(h, c)
      return {"iou": iou, "c": c}
  
imports: import itertools
  import time
  import dgl
  import mxnet
  import networkx
  import numpy
  from mxnet import gluon
label_desc: Use image node_id 2 for calling the TreeLSTMCell obj's underlying member method code with example usage: obj.reduce_func(nodes) and returns: dict