code: def test_graph_serialize_without_feature():
      num_graphs = 100
      g_list = [generate_rand_graph(30) for _ in range(num_graphs)]
  
      # create a temporary file and immediately release it so DGL can open it.
      f = tempfile.NamedTemporaryFile(delete=False)
      path = f.name
      f.close()
  
      dgl.save_graphs(path, g_list)
  
      idx_list = np.random.permutation(np.arange(num_graphs)).tolist()
      loadg_list, _ = dgl.load_graphs(path, idx_list)
  
      idx = idx_list[0]
      load_g = loadg_list[0]
  
      assert F.allclose(load_g.nodes(), g_list[idx].nodes())
  
      load_edges = load_g.all_edges("uv", "eid")
      g_edges = g_list[idx].all_edges("uv", "eid")
      assert F.allclose(load_edges[0], g_edges[0])
      assert F.allclose(load_edges[1], g_edges[1])
  
      os.unlink(path)
  
imports: import os
  import tempfile
  import time
  import unittest
  import warnings
  import backend
  import dgl
  import dgl.ndarray
  import numpy
  import pytest
  import scipy
  from dgl.data.utils import load_labels, load_tensors, save_tensors
label_desc: Use image node_id 4 for calling a global function with example usage: test_graph_serialize_without_feature() without return types