anchor.diff:      {ok, cowboy_req:reply(400, #{}, <<"Missing body.">>, Req), State};
   maybe_process(Req, State, <<"GET">>, Path, _) ->
       process_get(Req, State, Path);
  +aybe_process(REq, State, <<"HEAD">>, _, _) ->
  +    {ok, cowboy_req:reply(200, #{
  +        <<"content-type">> => <<"text/plain; charset=utf-8">>,
  +        <<"Access-Control-Allow-Origin">> => <<"*">>
  +    } , <<>>, Req), State};
   maybe_process(Req, _, _, _, _) ->
       %% Method not allowed.
       cowboy_req:reply(405, Req).
  
positive.code:         {Date, From, FirstChunk} ->
              Req1 = cowboy_req:stream_reply(200, #{
                  <<"Content-Type">> => <<"application/octet-stream">>,
                  <<"From">> => From,
                  <<"ETag">> => <<"\"", (integer_to_binary(Date))/binary, "\"">>
              }, Req),
  
negative.code:     case Answer of
          true ->
              {ok, cowboy_req:reply(200, #{
                  <<"content-type">> => <<"text/plain; charset=utf-8">>,
                  <<"Access-Control-Allow-Origin">> => <<"*">>
              }, format_out(Event, Out), Req), State};
          false ->
              cowboy_req:reply(409, Req)
  