code: def test_init_bad_variables_type(self):
      # variables is non-iterable
      self.assertRaises(ValueError, MC, variables=123)
      # variables is a string
      self.assertRaises(ValueError, MC, variables="abc")
  
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 4 for calling the TestMarkovChain obj's underlying member method code with example usage: obj.test_init_bad_variables_type() without return types