anchor.diff:                                              ListenerOpts,
                                               {Protocol, ProtoOpts, Spawn})
                    || _ <- lists:seq(1, NbAcceptors)],
  +
       {ok, #state{socket = Socket,
                   transport = Transport,
                   transport_opts = TransOpts,
  
positive.code:                 true ->
                      false;
                  false ->
                      io:format("error bad proto~n", []),
                      throw({error, bad_proto})
              end
      end.
  
negative.code:     [{nb_acceptors, Nb}] = info(Ref, [nb_acceptors]),
      Nb.
  
  start_accepting(Ref) ->
      gen_server:call(Ref, start_accepting, infinity).
  
  