anchor.diff:  lens_http_socket_peername() ->
      lens:c([lens:tuple(#http.state), lens_socket_peername()]).
   
  +lens_http_queue() ->
  +   lens:c([lens:tuple(#http.state), lens:tuple(#fsm.queue), lens_qhead()]).
  +
  +lens_qhead() ->
  +   fun(Fun, Queue) ->
  +      lens:fmap(fun(_) -> Queue end, Fun(q:head(Queue)))
  +   end.
  +
   
   
   %%
  
positive.code: 
  %%
  %%
  http_request_log(#http{is = eof, http = {response, _}, state = #fsm{queue = Q} = State} = Http) ->
     #req{
        http = {_, {Mthd,  Url, HeadA}}, 
        code = {_, {Code, _Msg, HeadB}}, 
        treq = T
     } = deq:head(Q),
     ?access_http(#{
        req  => {Mthd, Code}
       ,peer => lens:get(lens_http_socket_peername(), Http)
  
negative.code: %%
  %%
  down_link_return(Pipe, #http{is = eoh, state = State}) ->
     %% htstream has a feature of "eoh event".
     down_link([], Pipe, State);
  
  down_link_return(_Pipe, #http{state = State}) ->
  