anchor.diff:        instances.putIfAbsent(elementKind, () => _ElementKind._(elementKind));
   
     _ElementKind._(this.elementKind);
  +
  +  @override
  +  String get uniqueKey => 'e${elementKind.name}';
   }
   
   /// A wrapper for a keyword to allow keywords and element kinds to be used as
  
positive.code:       instances.putIfAbsent(keyword, () => _Keyword._(keyword));
  
    _Keyword._(this.keyword);
  }
  
  /// A superclass for [_ElementKind] and [_Keyword] to allow keywords and element
  /// kinds to be used as keys in a single table.
  class _Kind {}
  
negative.code: // 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 'dart:convert';
  import 'dart:io' as io;
  
  import 'package:_fe_analyzer_shared/src/base/syntactic_entity.dart';
  