anchor.diff:          {"Accept-Encoding", "identity"},
           {"Accept-Charset", "UTF-8;q=1.0, ISO-8859-1;q=0.5, *;q=0"},
           {"Accept-Language", "en,*;q=0"},
  -        {"User-Agent", httpc_ua(Url)},
  -        {"Connection", "close"}
  +        {"User-Agent", httpc_ua(Url)}
       ] ++ case Max of
               undefined -> [];
               _ -> [ {"Range", "bytes=0-"++integer_to_list(Max-1)} ]
  
positive.code:         {http, {_ReqId, {{_V, Code, _Msg}, Hs, Data}}} ->
              {ok, {Code, Hs, 0, Data}}
      after ?HTTPC_TIMEOUT ->
          httpc:cancel_request(ReqId), 
          {error, timeout}
      end;
  fetch_stream({error, _} = Error, _Max, _OutDev) ->
  
negative.code:     case string:tokens(Url, "://") of
          [_Proto, DomainPath | _] ->
              is_url_shortener_1(DomainPath);
          _ ->
              false
      end.
  
  