anchor.diff:  %% TODO confirm we shouldn't be able to get here by using -spec()
   parse(_, _Rest) ->
       {error, ppspp_message_type_not_parsable}.
  +
  +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  +%%-spec ... handle takes a parsed orddict message and returns either
  +%%    {error, something} or tagged tuple for the unpacked message
  +%%    {ok, reply} where reply is probably an orddict to be sent to the
  +%%    alternate peer.
  +handle(Message) -> {ok, reply}.
  
positive.code: -include_lib("eunit/include/eunit.hrl").
  -endif.
  
  -export([unpack/1, pack/1,validate_message_type/1]).
  
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  %% external API
  
negative.code:     unpack(Maybe_More_Messages, [Parsed_Message | Parsed_Messages]);
  unpack(_Maybe_Messages, _Rest) -> {error, ppspp_invalid_message}.
  
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  pack(_) -> ok.
  
  