code: def test_simple_list(self):
      G = nx.Graph()
      list_value = [(1, 2, 3), (9, 1, 2)]
      G.add_node(1, key=list_value)
      fh = io.BytesIO()
      nx.write_gexf(G, fh)
      fh.seek(0)
      H = nx.read_gexf(fh, node_type=int)
      assert H.nodes[1]["networkx_key"] == list_value
  
imports: import io
  import time
  import pytest
  import networkx
label_desc: Use image node_id 17 for calling the TestGEXF obj's underlying member method code with example usage: obj.test_simple_list() without return types