code: def test_subclass(self):
      class MyGraph(nx.DiGraph):
          def my_method(self):
              return "me"
  
          def to_directed_class(self):
              return MyGraph()
  
      for origG in self.graphs:
          G = MyGraph(origG)
          SG = G.subgraph([4, 5, 6])
          H = SG.copy()
          assert SG.my_method() == "me"
          assert H.my_method() == "me"
          assert 3 not in H or 3 in SG
  
imports: import pytest
  import networkx
  from networkx.utils import edges_equal, nodes_equal
label_desc: Use image node_id 16 for calling the TestChainsOfViews obj's underlying member method code with example usage: obj.test_subclass() and returns: str, MyGraph