anchor.diff:  
       i("start client evaluator"),
       Client = ?SEV_START("client", ClientSeq, InitState),
  -    i("await evaluator(s)"),
   
       i("start tester evaluator"),
       TesterInitState = #{server => Server#ev.pid,
                           client => Client#ev.pid},
       Tester = ?SEV_START("tester", TesterSeq, TesterInitState),
   
  +    i("await evaluator(s)"),
       ok = ?SEV_AWAIT_FINISH([Server, Client, Tester]).
   
   
  
positive.code:      api_a_send_and_recv_tcp4,
       api_a_sendmsg_and_recvmsg_tcp4,
       api_a_recvfrom_cancel_udp4,
       api_a_recvmsg_cancel_udp4%%,
       %% api_a_accept_cancel_tcp4,
       %% api_a_recv_cancel_tcp4,
       %% api_a_recvmsg_cancel_tcp4
      ].
  
negative.code:          #{desc => "try recv request (with nowait, expect select)",
             cmd  => fun(#{sock := Sock, recv := Recv} = State) ->
                             case Recv(Sock) of
                                 {ok, {select, _, _} = SelectInfo} ->
                                     {ok, State#{recv_select_info => SelectInfo}};
                                 {ok, X} ->
                                     {error, {unexpected_select_info, X}};
  