code: def test_get_cardinality(self):
      self.graph.add_edges_from(
          [
              ("a", "phi1"),
              ("b", "phi1"),
              ("c", "phi2"),
              ("d", "phi2"),
              ("a", "phi3"),
              ("d", "phi3"),
          ]
      )
  
      self.assertDictEqual(self.graph.get_cardinality(), {})
  
      phi1 = DiscreteFactor(["a", "b"], [1, 2], np.random.rand(2))
      self.graph.add_factors(phi1)
      self.assertDictEqual(
          self.graph.get_cardinality(), {"a": 1, "b": 2}
      )
      self.graph.remove_factors(phi1)
      self.assertDictEqual(self.graph.get_cardinality(), {})
  
      phi1 = DiscreteFactor(["a", "b"], [2, 2], np.random.rand(4))
      phi2 = DiscreteFactor(["c", "d"], [1, 2], np.random.rand(2))
      self.graph.add_factors(phi1, phi2)
      self.assertDictEqual(
          self.graph.get_cardinality(), {"d": 2, "a": 2, "b": 2, "c": 1}
      )
  
      phi3 = DiscreteFactor(["d", "a"], [1, 2], np.random.rand(2))
      self.graph.add_factors(phi3)
      self.assertDictEqual(
          self.graph.get_cardinality(), {"d": 1, "c": 1, "b": 2, "a": 2}
      )
  
      self.graph.remove_factors(phi1, phi2, phi3)
      self.assertDictEqual(self.graph.get_cardinality(), {})
  
imports: import numpy
  import unittest
  from pgmpy.factors.discrete import DiscreteFactor
  from pgmpy.models import FactorGraph
  from pgmpy.models import MarkovNetwork
  from pgmpy.models import JunctionTree
  from pgmpy.tests import help_functions
label_desc: Use image node_id 2 for calling the TestFactorGraphMethods obj's underlying member method code with example usage: obj.test_get_cardinality() without return types