code: def test_get_variables(self):
      var_expected = [
          "kid",
          "light_on",
          "bowel_problem",
          "dog_out",
          "hear_bark",
          "family_out",
      ]
      self.assertListEqual(self.reader.variables, var_expected)
  
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 2 for calling the TestXMLBIFReaderMethodsFileTorch obj's underlying member method code with example usage: obj.test_get_variables() without return types