anchor.diff:      end.
   
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  -% Serial Run
  +%% Serial Run
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   
   -spec bfs_serial(environment(), state(), #opts{}) -> answer() | answer_S().
  
positive.code: -module(search).
  -export([bfs/4, worker/2]).
  % CAUTION: worker needs to be exported if it is to be called from the shell
  
  -type state() :: _.
  -type environment() :: _.
  
negative.code:     Worker ! {state, State},
      send_states_tr(States, Workers, AllWorkers).
  
  -spec spawn_link_n(non_neg_integer(), atom(), atom(), [_,...]) -> [pid()].
  spawn_link_n(N, Module, Name, Args) ->
      spawn_link_n_tr(N, Module, Name, Args, []).
  
  -spec spawn_link_n_tr(non_neg_integer(), atom(), atom(), [_,...], [pid()]) ->
  	  [pid()].
  spawn_link_n_tr(0, _Module, _Name, _Args, Pids) ->
      Pids;
  