anchor.diff:  handle_call(get, _From, State) ->
       {reply, State, State};
   
  -handle_call({replace, KVList}, _From, State) ->
  -    {reply, ok, State#config{dynamic = [KVList]}};
  -
   handle_call({update_with_changes, Fun}, From, #config{uuid = UUID} = State) ->
       OldList = config_dynamic(State),
       try Fun(OldList, UUID) of
  
positive.code:     set([{K, ?DELETED_MARKER} || K <- Keys]);
  delete(Key) ->
      delete([Key]).
  
  replace(KVList) -> gen_server:call(?MODULE, {replace, KVList}).
  
  %% update config by applying Fun to it. Fun should return a pair
  %% {NewPairs, NewConfig} where NewConfig is new config and NewPairs is
  
negative.code: -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
           terminate/2, code_change/3]).
  
  -export([stop/0, resave/0, reannounce/0]).
  
  %% state sanitization
  -export([format_status/2]).
  