docs: def get_slice_nodes(self, time_slice=0):
          """
          Returns the nodes present in a particular timeslice
  
          Parameters
          ----------
          time_slice:int
                  The timeslice should be a positive value greater than or equal to 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))])
          >>> dbn.get_slice_nodes()
          """
          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 [(node, time_slice) for node in self._nodes()]