code: def num_nodes(self):
      return self.g.num_nodes()
  
imports: import argparse
  import textwrap
  import tensorflow
  import tensorflow_addons
  from dgl.data import CiteseerGraphDataset, CoraGraphDataset, PubmedGraphDataset
  from dgl.nn.tensorflow.conv import SGConv
label_desc: Use image node_id 4 for calling the SGC obj's underlying member method code with example usage: obj.num_nodes() and returns: self