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