code: def test_get_states(self):
      states_expected = {
          "bowel_problem": ["true", "false"],
          "dog_out": ["true", "false"],
          "family_out": ["true", "false"],
          "hear_bark": ["true", "false"],
          "kid": ["true", "false"],
          "light_on": ["true", "false"],
      }
      states = self.reader.variable_states
      for variable in states_expected:
          self.assertListEqual(
              states_expected[variable], states[variable]
          )
  
imports: import os
  import unittest
  import xml.etree.ElementTree
  import numpy
  import numpy.testing
  from pgmpy import config
  from pgmpy.factors.discrete import TabularCPD
  from pgmpy.models import BayesianNetwork
  from pgmpy.readwrite import XMLBIFReader, XMLBIFWriter
label_desc: Use image node_id 3 for calling the TestXMLBIFReaderMethodsFile obj's underlying member method code with example usage: obj.test_get_states() without return types