code: def gcn_reduce(node):
      accum = tf.reduce_sum(node.mailbox["m"], 1) * node.data["norm"]
      return {"h": accum}
  
imports: import argparse
  import math
  import time
  import dgl
  import networkx
  import numpy
  import tensorflow
  from dgl.data import CiteseerGraphDataset, CoraGraphDataset, PubmedGraphDataset, register_data_args
  from tensorflow.keras import layers
label_desc: Use image node_id 2 for calling a global function with example usage: gcn_reduce(node) and returns: dict