anchor.diff:      return;
     }
   
  +  final concurrency = int.parse(argv['concurrency'] as String);
     final package = argv['package'] as String;
     await withProdServices(() async {
       registerAccountBackend(AccountBackend(dbService));
  
positive.code: import 'package:pub_dartlang_org/frontend/service_utils.dart';
  
  final _argParser = new ArgParser()
    ..addOption('package', abbr: 'p', help: 'The package to backfill.')
    ..addFlag('help', abbr: 'h', defaultsTo: false, help: 'Show help.');
  
  final _emailToUser = <String, User>{};
  final _userFirstUsed = <String, DateTime>{};
  
  
negative.code:     if (package != null) {
        await _backfillPackage(package);
      } else {
        final pool = Pool(concurrency);
        final futures = <Future>[];
  
        await for (Package p in dbService.query<Package>().run()) {
          final f = pool.withResource(() => _backfillPackage(p.name));
          futures.add(f);
        }
  
        await Future.wait(futures);
        await pool.close();
      }
  
      for (User user in _emailToUser.values) {
  