anchor.diff:          {event, <<"myevent4;id=4;o=2">>},
           {class, uac},
           {answered, undefined},
  -        {expires, 1}    % It will be something link round(0.99)
  +        {expires, 1}    % It shuould be something like round(0.99)
       ] = nksip_subscription:fields(C1, Subs1A, [status, event, class, answered, expires]),
   
       [
  
positive.code:     % Another subscription
      {async, _} = 
          nksip_uac:subscribe(C1, SipC2, [{event, "myevent4"}, CB, async, get_request,
                                          {add, Reply}, {add, "x-nk-op", "wait"}, 
                                          {expires, 2}]),
      RecvReq2 = receive {Ref, {wait, Req2}} -> Req2
      after 1000 -> error(fork)
  
negative.code:         nksip_uac:subscribe(C1, SipC2, [{event, "myevent1;id=a"}, CB, get_request]),
  
      receive {Ref, {req, Req1}} -> 
          [[<<"myevent1;id=a">>],[<<"myevent1,myevent2,myevent3">>]] = 
              nksip_sipmsg:fields(Req1, [<<"event">>, <<"allow-event">>])
      after 1000 -> 
          error(event) 
      end,
  