anchor.diff:  
   %% API
   -export([start_link/4
  +         ,shutdown/1
           ]).
   
   %% gen_server callbacks
  
positive.code:     {noreply, State}.
  
  %% @private
  handle_cast(Msg, State) ->
      ?WARN("drain_id=~p channel_id=~p dest=~s err=unexpected_cast data=~p",
            log_info(State, [Msg])),
  
negative.code:                                   port=Port}],
                            []).
  
  shutdown(Pid) ->
      gen_server:cast(Pid, shutdown),
      ok.
  %%====================================================================
  %% gen_server callbacks
  %%====================================================================
  