anchor.diff:      %% Server
       %%
       %% ?P("[server] sending..."),
  -    Master ! {self(), send},
       case gen_tcp:send(S, Msg) of
   	ok ->
  +            Master ! {self(), send},
   	    %% ?P("[server] ok."),
   	    fill_sendq_write(S, Master, Msg);
   	{error, _} = E ->
  
positive.code:     ?P("[server] await accept"),
      case gen_tcp:accept(L) of
  	{ok, S} ->
  	    Master ! {self(),reader,
  		      spawn_link(fun () -> fill_sendq_read(S, Master) end)},
  	    Msg = "the quick brown fox jumps over a lazy dog~n",
  	    fill_sendq_write(S, Master, [Msg,Msg,Msg,Msg,Msg,Msg,Msg,Msg]);
  
negative.code: %%% Fill send queue
  %%%
  fill_sendq(Config) when is_list(Config) ->
      ?TC_TRY(fill_sendq, fun() -> do_fill_sendq(Config) end).
  
  do_fill_sendq(_Config) ->
      OldFlag = process_flag(trap_exit, true),
  