// given a class graph, find all concrete subclasses of a given class
*operation* Vertex_List* find_assoc(Vertex* v)
  *init* (@ new Vertex_List(); @)
*wrapper* CdGraph
  *prefix* (@ this -> find_associated(return_val, v, this); @)

*operation* void find_associated(Vertex_List* l, Vertex* v, CdGraph* cd)
  *init* (@ new Vertex_List(); @)
*traverse*
  *merge* (
    *from* CdGraph *to* C,
    *from* CdGraph *through* -> *,alternatNs,* *to* Vertex)

// can replace with bypassing in this case
// but this is much less intuitive => merge is a useful operator
//*from* CdGraph 
//  *bypassing* -> *,constructNs,* ,
//              -> *,source,* 
//*to* {Vertex, C}

*wrapper* Adjacency 
  *prefix* (@ if (source->g_equal(v)) { @)
  *suffix* (@ } @)

*wrapper* C
  *prefix* (@ l -> append((Vertex *)(v -> g_copy()));
    cout << "\n Vertex appended" << v; @)

*wrapper* Vertex
  *prefix* (@ cd -> find_associated(l, this, cd); @)