docs: def get_intra_edges(self, time_slice=0):
          """
          Returns the intra slice edges present in the 2-TBN.
  
          Parameter
          ---------
          time_slice: int (whole number)
                  The time slice for which to get intra edges. The timeslice
                  should be a positive value or zero.
  
          Examples
          --------
          >>> from pgmpy.models import DynamicBayesianNetwork as DBN
          >>> dbn = DBN()
          >>> dbn.add_nodes_from(['D', 'G', 'I', 'S', 'L'])
          >>> dbn.add_edges_from([(('D', 0), ('G', 0)), (('I', 0), ('G', 0)),
          ...                     (('G', 0), ('L', 0)), (('D', 0), ('D', 1)),
          ...                     (('I', 0), ('I', 1)), (('G', 0), ('G', 1)),
          ...                     (('G', 0), ('L', 1)), (('L', 0), ('L', 1))])
          >>> dbn.get_intra_edges()
          [(('D', 0), ('G', 0)), (('G', 0), ('L', 0)), (('I', 0), ('G', 0))
          """
          if not isinstance(time_slice, int) or time_slice < 0:
              raise ValueError("The timeslice should be a positive value greater than or equal to zero")
  
          return [tuple((x[0], time_slice) for x in edge) for edge in self.edges() if edge[0][1] == edge[1][1] == 0]