anchor.diff:      gen_server:call(wrangler_preview_server, commit).
   
   %%-spec(abort/0::() ->{ok, [filename()]}).
  +
  +abort(_IsCompositeRefac) -> %% This function will be extended!
  +    gen_server:call(wrangler_preview_server, abort).
   abort() ->
       gen_server:call(wrangler_preview_server, abort).
      
  
positive.code: handle_call(abort, _From, #state{files=Files}) ->
      SwpFiles = lists:flatmap(fun ({{F1, F2, IsNew}, Swp}) ->
  				     case IsNew of
  				       false -> [Swp];
  				       _ -> case F1 == F2 of
  					      true -> [F1, Swp];
  					      _ -> [F1, F2, Swp]
  					    end
  				     end
  			     end, Files),
      {reply, {ok, SwpFiles}, #state{files=[], logmsg=""}};
  
negative.code: -behaviour(gen_server).
  
  %% API
  -export([commit/0, abort/0, abort/1,add_files/1, start_preview_server/0]).
  
  %% gen_server callbacks
  -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
  