anchor.diff:  server_opts({T, Addr, Port}) ->
       [{transport_module, tmod(T)},
        {transport_config, [{reuseaddr, true},
  +                         {sender, true},
  +                         {message_cb, [fun ?MODULE:message/3, 0]},
                            {ip, addr(Addr)},
                            {port, Port}]}];
   
  
positive.code:     {127,0,0,1};
  addr(A) ->
      A.
  
negative.code:          connect/2,
           stop/1]).
  
  -export([message/3]).
  
  -type protocol()
     :: tcp | sctp.
  
  