code: def get_subgraph(self, name):
          
  
          match = list()
  
          if name in self.obj_dict['subgraphs']:
  
              sgraphs_obj_dict = self.obj_dict['subgraphs'].get( name )
  
              for obj_dict_list in sgraphs_obj_dict:
                  #match.extend( Subgraph( obj_dict = obj_d )
                  #             for obj_d in obj_dict_list )
                  match.append( Subgraph( obj_dict = obj_dict_list ) )
  
          return match
docs: Retrieved a subgraph from the graph.
  
          Given a subgraph's name the corresponding
          Subgraph instance will be returned.
  
          If one or more subgraphs exist with the same name, a list of
          Subgraph instances is returned.
          An empty list is returned otherwise.