code: def test_class_init_without_data(self):
      self.assertIsInstance(self.graph, UndirectedGraph)
  
imports: from pgmpy.base import UndirectedGraph
  from pgmpy.tests import help_functions
  import unittest
label_desc: Use image node_id 2 for calling the TestUndirectedGraphCreation obj's underlying member method code with example usage: obj.test_class_init_without_data() without return types