anchor.diff:  %% for C API (http://msgpack.sourceforge.jp/c:doc)
   %% except buffering functions (both copying and zero-copying).
   -export([pack/1, unpack/1, unpack_all/1]).
  +-export([pack_map/1]).
   
   % compile:
   % erl> c(msgpack).
  
positive.code: 	     -234.4355, 1.0e-34, 1.0e64,
  	     [23, 234, 0.23],
  	     [0,42,<<"sum">>, [1,2]], [1,42, nil, [3]],
  	     dict:from_list([{1,2},{<<"hoge">>,nil}]),
  	     -234, -50000,
  	     42
  	    ],
  
negative.code: 	{Term, Rest}-> unpack_array_(Rest, RestLen-1, [Term|RetList])
      end.
  
  pack_map_([], Acc) -> Acc;
  pack_map_([{Key,Value}|Tail], Acc) ->
      pack_map_(Tail, << Acc/binary, (pack(Key))/binary, (pack(Value))/binary>>).
  