code: def test_subgraph_toundirected(self):
      SG = nx.induced_subgraph(self.G, [4, 5, 6])
      SSG = SG.to_undirected()
      assert list(SSG) == [4, 5, 6]
      assert sorted(SSG.edges) == [(4, 5), (5, 6)]
  
imports: import pytest
  import networkx
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 7 for calling the TestChainsOfViews obj's underlying member method code with example usage: obj.test_subgraph_toundirected() without return types