//
// alternation_vertices
//
// returns a list of all the alternation vertices in the class dictionary
//

*operation* Vertex_comma_list* alternation_vertices()
  *init* (@ new Vertex_comma_list @)
  *traverse* *from* Cd_graph
             *via*  Adjacency
             *to*   Alternat_ns
  *carry* *in* Vertex* src = (@ source @)
    *along* *from* Adjacency *to* Alternat_ns
  *wrapper* Alternat_ns
    *suffix*  (@ return_val->append(src); @)