anchor.diff:  -type validator_result() :: ('ok' | {'fail', _}).
   -type validator() :: fun((wallaroo_tree:tree(), module()) -> validator_result()).
   -export_type([validator_result/0, validator/0]).
  +
  +-include("dlog.hrl").
   
   succeed(_Tree, _StoreMod) ->
       ok.
  
positive.code: 	{result_for, Pid, ok} ->
  	    handle_success(Pid, Pids, Failures, Failfast);
  	{result_for, Pid, {fail, _}=Failure} ->
  	    handle_failure(Pid, Pids, Failure, Failures, Failfast);
  	X ->
  	    handle_failure(unknown, Pids, {fail, {other_validator_result, X}}, Failures, Failfast)	    
      end.
  
  
negative.code: pcompose_loop([], [Failure], _) ->
      Failure;
  pcompose_loop([], Failures, _) ->
      ?D_LOG("pcompose_loop/3: failures are ~p~n", [Failures]),
      {fail, 
       {multiple_failures, 
        lists:foldl(fun({fail, {multiple_failures, Ls}}, Acc) ->
  