anchor.diff:  reset_features(S, [Id], _) ->
     [ {(get_socket(S, Id))#socket.tcp_state, '->', closed} ].
   
  -sent_syn_callouts(_, [Id]) ->
  +send_syn_callouts(_, [Id]) ->
     ?MATCH(Packet, ?APPLY(sent, [Id])),
     Port = {call, erlang, element, [#pkt.sport, Packet]},
     ?ASSERT(?MODULE, check_packet, [Packet, '_', '_', [syn]]),
  
positive.code:        , ?APPLY(sent_ack, [Id]) ]),
    ?SET(Id, tcp_state, established).
  
  %% --- listen ---
  
  listen_pre(S) ->
    length(S#state.sockets) < ?MAX_SOCKETS.
  
negative.code:   ?INC(Id, seq),
    ?RET(ok).
  
  send_syn_ack_callouts(S, [Id]) ->
    Sock = get_socket(S, Id),
    ?MATCH(Packet, ?APPLY(sent, [Id])),
    ?ASSERT(?MODULE, check_packet, [Packet, '_', Sock#socket.rseq, [ack, syn]]),
  