anchor.diff:  %% Function: log(Tag, Size) -> ok
   %% Description: logs a message type with its size
   %%--------------------------------------------------------------------
  +-spec log(atom(), integer()) -> ok.
   log(Tag, Size) ->
       gen_server:cast(?MODULE, {log, Tag, Size}).
   
  
positive.code: 
  -behaviour(gen_server).
  
  %% API
  -export([start_link/0]).
  
  
negative.code: %% cleaning up. When it returns, the gen_server terminates with Reason.
  %% The return value is ignored.
  %%--------------------------------------------------------------------
  -spec terminate(any(), #state{}) -> ok.
  terminate(_Reason, _State) ->
      ok.
  
  