code: def setUp(self):
      self.graph = ClusterGraph()
  
imports: import unittest
  import numpy
  from pgmpy.factors.discrete import DiscreteFactor
  from pgmpy.models import ClusterGraph
  from pgmpy.tests import help_functions
label_desc: Use image node_id 1 for calling the TestClusterGraphCreation obj's underlying member method code with example usage: obj.setUp() without return types