code: def test_check_model1(self):
      self.graph.add_edges_from(
          [(("a", "b"), ("a", "c")), (("a", "c"), ("a", "d"))]
      )
      phi1 = DiscreteFactor(["a", "b"], [1, 2], np.random.rand(2))
      self.graph.add_factors(phi1)
      self.assertRaises(ValueError, self.graph.check_model)
      phi2 = DiscreteFactor(["a", "c"], [1, 2], np.random.rand(2))
      self.graph.add_factors(phi2)
      self.assertRaises(ValueError, self.graph.check_model)
  
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 5 for calling the TestClusterGraphMethods obj's underlying member method code with example usage: obj.test_check_model1() without return types