code: def test_copy(self):
      model = MC(["a", "b"], [2, 2], [State("a", 0), State("b", 1)])
      model.add_transition_model(
          "a", {0: {0: 0.1, 1: 0.9}, 1: {0: 0.2, 1: 0.8}}
      )
      model.add_transition_model(
          "b", {0: {0: 0.3, 1: 0.7}, 1: {0: 0.4, 1: 0.6}}
      )
      copy = model.copy()
  
      self.assertIsInstance(copy, MC)
      self.assertEqual(sorted(model.variables), sorted(copy.variables))
      self.assertEqual(model.cardinalities, copy.cardinalities)
      self.assertEqual(model.transition_models, copy.transition_models)
      self.assertEqual(model.state, copy.state)
  
      model.add_variable("p", 1)
      model.set_start_state(
          [State("a", 0), State("b", 1), State("p", 0)]
      )
      model.add_transition_model("p", {0: {0: 1}})
  
      self.assertNotEqual(
          sorted(model.variables), sorted(copy.variables)
      )
      self.assertEqual(sorted(["a", "b"]), sorted(copy.variables))
      self.assertNotEqual(model.cardinalities, copy.cardinalities)
      self.assertEqual({"a": 2, "b": 2}, copy.cardinalities)
      self.assertNotEqual(model.state, copy.state)
      self.assertEqual([State("a", 0), State("b", 1)], copy.state)
      self.assertNotEqual(
          model.transition_models, copy.transition_models
      )
      self.assertEqual(len(copy.transition_models), 2)
      self.assertEqual(
          copy.transition_models["a"],
          {0: {0: 0.1, 1: 0.9}, 1: {0: 0.2, 1: 0.8}},
      )
      self.assertEqual(
          copy.transition_models["b"],
          {0: {0: 0.3, 1: 0.7}, 1: {0: 0.4, 1: 0.6}},
      )
  
imports: import sys
  import unittest
  import numpy
  from mock import call, patch
  from pandas import DataFrame
  from pgmpy.factors.discrete import State
  from pgmpy.models import MarkovChain
label_desc: Use image node_id 14 for calling the TestMarkovChain obj's underlying member method code with example usage: obj.test_copy() without return types