code: def test_add_edge_with_farther_timeslice(self):
      self.assertRaises(
          ValueError, self.network.add_edge, ("a", 2), ("b", 4)
      )
  
imports: import unittest
  import numpy
  import numpy.testing
  import pandas
  import pgmpy.tests.help_functions
  from pgmpy.factors.discrete import TabularCPD
  from pgmpy.inference import CausalInference, DBNInference, VariableElimination
  from pgmpy.models import BayesianNetwork
  from pgmpy.models import DynamicBayesianNetwork
label_desc: Use image node_id 7 for calling the TestDynamicBayesianNetworkCreation obj's underlying member method code with example usage: obj.test_add_edge_with_farther_timeslice() without return types