docs: def add_edge(self, u, v, **kwargs):
          """
          Add an edge between two clique nodes.
  
          Parameters
          ----------
          u, v: nodes
              Nodes can be any list or set or tuple of nodes forming a clique.
  
          Examples
          --------
          >>> from pgmpy.models import ClusterGraph
          >>> G = ClusterGraph()
          >>> G.add_nodes_from([('a', 'b', 'c'), ('a', 'b'), ('a', 'c')])
          >>> G.add_edges_from([(('a', 'b', 'c'), ('a', 'b')),
          ...                   (('a', 'b', 'c'), ('a', 'c'))])
          """
          set_u = set(u)
          set_v = set(v)
          if set_u.isdisjoint(set_v):
              raise ValueError('No sepset found between these two edges.')
  
          super(ClusterGraph, self).add_edge(u, v)