code: def test_subgraph_of_subgraph(self):
      SGv = nx.subgraph(self.G, range(3, 7))
      SDGv = nx.subgraph(self.DG, range(3, 7))
      SMGv = nx.subgraph(self.MG, range(3, 7))
      SMDGv = nx.subgraph(self.MDG, range(3, 7))
      for G in self.graphs + [SGv, SDGv, SMGv, SMDGv]:
          SG = nx.induced_subgraph(G, [4, 5, 6])
          assert list(SG) == [4, 5, 6]
          SSG = SG.subgraph([6, 7])
          assert list(SSG) == [6]
          # subgraph-subgraph chain is short-cut in base class method
          assert SSG._graph is G
  
imports: import pytest
  import networkx
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 3 for calling the TestChainsOfViews obj's underlying member method code with example usage: obj.test_subgraph_of_subgraph() without return types