anchor.diff:         [S#state.socket, S#state.id]).
   
   close_pre(Ss, [Socket, Id]) ->
  -  [ S ] = [ S || S<-Ss, S#state.id == Id ],
  -  S#state.socket == Socket andalso
  -    in_tcp_state(Ss, Id, [established, close_wait, listen]) andalso
  -    lists:member(S#state.socket_type, [accept, connect]).
  +  case [ S || S<-Ss, S#state.id == Id ] of
  +    [ S ] ->
  +      S#state.socket == Socket andalso
  +        in_tcp_state(Ss, Id, [established, close_wait, listen]) andalso
  +        lists:member(S#state.socket_type, [accept, connect, listen]);
  +    _ ->
  +      false
  +  end.
   
   closet_adapt(Ss, [_, Id]) -> 
  -  [ S ] = [ S || S<-Ss, S#state.id == Id ],
  -  [S#state.socket, Id].
  +  case [ S || S<-Ss, S#state.id == Id ] of
  +    [ S ] ->
  +      [S#state.socket, Id];
  +    _ ->
  +      false
  +  end.
   
   close(Socket, _) ->
     Root = self(),
  
positive.code:   ok.
  
  syn_pre(Ss, [Ip, Port, _, _, _, Id]) ->
    [ S ] = [ S || S<-Ss, S#state.id == Id ],
    S#state.ip   == Ip andalso
    S#state.port == Port andalso
      in_tcp_state(Ss, Id, listen).
  
  syn_adapt(Ss, [_, _, Ip, Port, Seq, Id]) ->
    [ S ] = [ S || S<-Ss, S#state.id == Id ],
    [S#state.ip, S#state.port, Ip, Port, Seq, Id].
  
  syn_callouts(_S, [_Ip,  _Port, RemoteIp, RemotePort, RemoteSeq, Id]) ->
    ?SET(Id, rip, RemoteIp),
  
negative.code:     Ack   == S#state.rcvd.
      
  fin_adapt(Ss, [_, _, _, _, _, _, Id]) -> 
    case [ S || S<-Ss, S#state.id == Id ] of
      [ S ] ->
        [S#state.ip, S#state.port,
         S#state.rip, S#state.rport,
         S#state.rseq, S#state.rcvd, Id];
      _ ->
        false
    end.
  
  fin(Ip, Port, RemoteIp, RemotePort, Seq, Ack, _) ->
    Packet =
  