code: def test_virtual_evidence(self):
      res1 = self.infer.query(
          [("Y", 4)],
          virtual_evidence=[TabularCPD(("Y", 2), 2, [[0.2], [0.8]])],
      )
      expected1 = DiscreteFactor([("Y", 4)], [2], [0.2205, 0.7795])
      self.assertTrue(res1.__eq__(expected1, atol=0.01))
  
imports: import unittest
  from pgmpy import config
  from pgmpy.factors.discrete import DiscreteFactor, TabularCPD
  from pgmpy.inference import ApproxInference, VariableElimination
  from pgmpy.models import DynamicBayesianNetwork
  from pgmpy.utils import get_example_model
label_desc: Use image node_id 4 for calling the TestApproxInferenceDBN obj's underlying member method code with example usage: obj.test_virtual_evidence() without return types