code: def test_node_iter(self):
      np_graph = create_random_bigraph().numpy()
      pd_graph = create_random_bigraph().tensor()
  
      for graph in [np_graph, pd_graph]:
          assert len(graph.src_nodes) == graph.src_num_nodes
          assert len(graph.dst_nodes) == graph.dst_num_nodes
          for shuffle in [True, False]:
              for m in ["src_node", "dst_node"]:
                  for batch_data in graph.node_batch_iter(
                      batch_size=3, shuffle=shuffle, mode=m
                  ):
                      break
  
imports: import os
  import unittest
  import numpy
  import paddle
  import pgl
  from testsuite import create_random_bigraph
label_desc: Use image node_id 13 for calling the BiGraphTest obj's underlying member method code with example usage: obj.test_node_iter() without return types