anchor.diff:      {ok, BuiltinResults} = builtin_reduce(reduce, BuiltinReds, KVs, []),
       recombine_reduce_results(RedSrcs, OsResults, BuiltinResults, []).
   
  -replace_builtin_equivalents([<<"_", _/binary>> = R | Rest]) ->
  -    [R | replace_builtin_equivalents(Rest)];
  -replace_builtin_equivalents([OsFun | Rest]) ->
  -    case re:run(OsFun, ?SUMREGEX) of nomatch ->
  -        case re:run(OsFun, ?COUNTREGEX) of nomatch ->
  -            [OsFun | replace_builtin_equivalents(Rest)];
  -        {match, _} ->
  -            [<<"_count">> | replace_builtin_equivalents(Rest)]
  -        end;
  -    {match, _} ->
  -        [<<"_sum">> | replace_builtin_equivalents(Rest)]
  -    end;
  -replace_builtin_equivalents([]) ->
  -    [].
   
   recombine_reduce_results([], [], [], Acc) ->
       {ok, lists:reverse(Acc)};
  
positive.code: 
  -define(STATERROR, <<"The _stats function requires that map values be numbers "
      "or arrays of numbers, not '~p'">>).
  
  % https://gist.github.com/df10284c76d85f988c3f
  -define(SUMREGEX, {re_pattern,3,0,<<69,82,67,80,194,0,0,0,8,0,0,0,5,0,0,0,3,0,
  2,0,0,0,125,2,48,0,9,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,118,97,108,
  117,101,115,0,93,0,130,65,9,27,102,27,117,27,110,27,99,27,116,27,105,27,111,27,
  110,102,94,0,9,0,1,66,9,58,11,84,0,9,65,9,27,40,65,9,58,11,65,9,27,44,56,9,94,
  0,7,0,2,58,11,84,0,7,102,94,0,15,0,3,65,9,27,44,65,9,58,11,56,9,84,0,15,65,9,
  27,41,65,9,27,123,65,9,27,114,27,101,27,116,27,117,27,114,27,110,66,9,27,115,
  27,117,27,109,65,9,27,40,56,9,80,0,2,65,9,27,41,56,9,34,59,65,9,27,125,56,9,84,
  0,130,0,0,0,0>>}).
  
  % https://gist.github.com/cbd73238b671325f5a6f
  -define(COUNTREGEX, {re_pattern,8,0,<<69,82,67,80,30,2,0,0,8,0,0,0,5,0,0,0,8,0,
  4,0,0,0,125,2,48,0,11,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,114,101,
  114,101,100,117,99,101,0,0,2,118,97,108,117,101,115,0,101,0,93,1,206,65,9,27,
  102,27,117,27,110,27,99,27,116,27,105,27,111,27,110,102,94,0,9,0,1,66,9,58,11,
  84,0,9,65,9,27,40,65,9,58,11,65,9,27,44,56,9,94,0,7,0,2,58,11,84,0,7,102,94,0,
  23,0,3,65,9,27,44,56,9,94,0,7,0,4,58,11,84,0,7,56,9,84,0,23,65,9,27,41,65,9,27,
  123,56,9,94,0,136,0,5,94,0,128,0,6,27,105,27,102,65,9,27,40,56,9,80,0,4,65,9,
  27,41,56,9,34,123,65,9,27,114,27,101,27,116,27,117,27,114,27,110,66,9,27,115,
  27,117,27,109,65,9,27,40,56,9,80,0,2,65,9,27,41,56,9,34,59,56,9,34,125,65,9,27,
  101,27,108,27,115,27,101,56,9,34,123,65,9,27,114,27,101,27,116,27,117,27,114,
  27,110,58,9,80,0,2,65,9,27,46,65,9,27,108,27,101,27,110,27,103,27,116,27,104,
  56,9,34,59,56,9,34,125,84,0,128,83,0,138,94,0,132,0,7,27,105,27,102,65,9,27,40,
  65,9,27,33,56,9,80,0,4,65,9,27,41,56,9,34,123,65,9,27,114,27,101,27,116,27,117,
  27,114,27,110,58,9,80,0,2,65,9,27,46,65,9,27,108,27,101,27,110,27,103,27,116,
  27,104,56,9,34,59,56,9,34,125,65,9,27,101,27,108,27,115,27,101,56,9,34,123,65,
  9,27,114,27,101,27,116,27,117,27,114,27,110,66,9,27,115,27,117,27,109,65,9,27,
  40,56,9,80,0,2,65,9,27,41,56,9,34,59,56,9,34,125,84,0,132,83,0,84,94,0,78,0,8,
  27,114,27,101,27,116,27,117,27,114,27,110,58,9,80,0,4,65,9,27,63,65,9,27,115,
  27,117,27,109,65,9,27,40,56,9,80,0,2,65,9,27,41,65,9,27,58,56,9,80,0,2,65,9,27,
  46,65,9,27,108,27,101,27,110,27,103,27,116,27,104,56,9,34,59,84,0,78,84,1,102,
  65,9,27,125,56,9,84,1,206,0,0,0,0,0,0,0>>}).
  
  
  try_compile(Proc, FunctionType, FunctionName, FunctionSource) ->
  
negative.code:             Result;
          (FunSrc, Values) ->
              os_rereduce(Lang, [FunSrc], Values)
          end, RedSrcs, Grouped),
      {ok, Results}.
  
  reduce(_Lang, [], _KVs) ->
      {ok, []};
  reduce(Lang, RedSrcs, KVs) ->
      {OsRedSrcs, BuiltinReds} = lists:partition(fun
          (<<"_", _/binary>>) -> false;
          (_OsFun) -> true
  