anchor.diff:  %%
   encode_version({Major, Minor}) ->
      <<$H, $T, $T, $P, $/, (encode_value(Major))/binary, $., (encode_value(Minor))/binary>>.
  +
  +%%
  +encode_url(undefined) ->
  +   <<$/>>;
  +encode_url(Url)
  + when is_binary(Url) ->
  +   Url.
   
   %%
   %%
  
positive.code: encode(Pckt, Acc, #http{is=entity, length=Len}=S)
   when is_integer(Len), size(Pckt) < Len ->
     {lists:reverse([Pckt  | Acc]), S#http{length=Len - size(Pckt)}};
     
  encode(Pckt, Acc, #http{is=entity, length=Len}=S)
   when is_integer(Len) ->
     %% TODO: preserve Rest to sndbuf
  
negative.code:       [Type]           -> {Type, '*'}
     end.
  
  
  %%%------------------------------------------------------------------
  %%%
  %%% encoder
  