code: def test_do(self):
      dag_do_x = self.g1.do("A")
      self.assertEqual(set(dag_do_x.nodes()), set(self.g1.nodes()))
      self.assertEqual(
          sorted(list(dag_do_x.edges())), [("A", "B"), ("A", "Y")]
      )
  
      dag_do_x = self.g2.do(["A", "Y"])
      self.assertEqual(set(dag_do_x.nodes()), set(self.g2.nodes()))
      self.assertEqual(sorted(list(dag_do_x.edges())), [("A", "B")])
  
imports: import unittest
  import networkx
  import numpy
  import pgmpy.tests.help_functions
  from pgmpy.base import DAG, PDAG
label_desc: Use image node_id 2 for calling the TestDoOperator obj's underlying member method code with example usage: obj.test_do() without return types