anchor.diff:  -behaviour(gen_server).
   
   %% API
  --export([start_link/2, build/1, emit/3, done/1, start/2]).
  +-export([start_link/3, build/1, emit/3, done/1, start/2]).
   
   %% gen_server callbacks
   -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
  
positive.code: %%                                   {stop, Reason, State}
  %% @end
  %%--------------------------------------------------------------------
  handle_call(_Request, _From, State) ->
      Reply = ok,
      {reply, Reply, State}.
  
negative.code: %% @spec start_link() -> {ok, Pid} | ignore | {error, Error}
  %% @end
  %%--------------------------------------------------------------------
  start_link(Parent, Query, Queries) ->
      gen_server:start_link(?MODULE, [Parent, Query, Queries], []).
  
  emit(Parents, Data, Resolution) ->
      [gen_server:cast(Parent, {emit, Ref, Data, Resolution}) ||
  