code: def forward(self):
      args = self.args
  
      graph_wrapper = pgl.graph_wrapper.GraphWrapper(
          "sub_graph",
          node_feat=[("feats", [None, 602], np.dtype("float32"))],
      )
      loss, acc = build_graph_model(
          graph_wrapper,
          num_class=args.num_class,
          hidden_size=args.hidden_size,
          graphsage_type=args.graphsage_type,
          k_hop=len(args.samples),
      )
  
      loss.persistable = True
  
      self.graph_wrapper = graph_wrapper
      self.loss = loss
      self.acc = acc
      return loss
  
imports: from __future__ import division
  from __future__ import absolute_import
  from __future__ import print_function
  from __future__ import unicode_literals
  import math
  import pgl
  import numpy
  import paddle
  import paddle.fluid.layers
  import paddle.fluid
  import paddle.fluid
label_desc: Use image node_id 2 for calling the GraphsageModel obj's underlying member method code with example usage: obj.forward() and returns: loss