code: def test_get_all_nodes(self):
      for flag in [True, False]:
          print(list(self.graph_obj._graph.nodes))
          print(list(self.nx_graph.nodes))
          res1 = self.graph_obj.get_all_nodes(include_unobserved=flag)
          res2 = get_all_nodes(
              self.nx_graph,
              self.observed_nodes,
              include_unobserved_nodes=flag,
          )
          assert set(res1) == set(res2)
  
imports: import networkx
  import pandas
  import pytest
  from flaky import flaky
  from pytest import mark
  import dowhy
  import dowhy.datasets
  from dowhy import CausalModel
  from dowhy.graph import *
  from dowhy.utils.graph_operations import daggity_to_dot
label_desc: Use image node_id 7 for calling the TestCausalGraph obj's underlying member method code with example usage: obj.test_get_all_nodes() without return types