anchor.diff:  // for details. All rights reserved. Use of this source code is governed by a
   // BSD-style license that can be found in the LICENSE file.
   
  -import 'package:uuid/uuid.dart';
  +import 'dart:math' as math;
   
   /// Generator generates ids that are probably unique.
   abstract class IdGenerator {
  
positive.code:   /// so it can be freely used anywhere across the app
    /// advantage: very likely to be unique without extra restrictions
    /// disadvantage: long ids
    SequentialIdGenerator.fromUUID() : this(_uuid.v4());
  
    @override
    String nextId() => "$_prefix--${_seq++}";
  }
  
negative.code: /// Sequential implementation of generator that will use seed as prefix
  /// and sequential number as suffix in form of "prefix--153"
  class SequentialIdGenerator implements IdGenerator {
    static final _rnd = new math.Random.secure();
    final String _prefix;
    int _seq = 0;
  
  