anchor.diff:  
   -include("emqtt_packet.hrl").
   
  --export([to_packet/1]).
  +-export([from_packet/1, to_packet/1]).
   
   %%----------------------------------------------------------------------------
   
  
positive.code: 
  -spec( to_packet( mqtt_message() ) -> mqtt_packet() ).
  
  -endif
  
  %%----------------------------------------------------------------------------
  
  from_packet(#mqtt_packet{ header = #mqtt_packet_header{ type   = ?PUBLISH,
                                                          qos    = Qos, 
                                                          retain = Retain, 
  
negative.code:                    dup     = false, 
                     payload = Msg }.
  
  %%
  %% @doc message to packet
  %%
  to_packet(#mqtt_message{ msgid   = MsgId,
                           qos     = Qos,
                           retain  = Retain,
  