anchor.diff:  import 'package:analyzer/dart/element/element.dart';
   import 'package:analyzer/dart/element/nullability_suffix.dart';
   import 'package:analyzer/dart/element/type.dart';
  -import 'package:analyzer/dart/element/type_provider.dart';
   import 'package:analyzer/src/dart/analysis/experiments.dart';
   import 'package:analyzer/src/dart/analysis/session.dart';
   import 'package:analyzer/src/dart/element/element.dart';
   import 'package:analyzer/src/dart/element/type.dart';
  -import 'package:analyzer/src/dart/element/type_system.dart';
   import 'package:analyzer/src/dart/resolver/variance.dart';
  -import 'package:analyzer/src/generated/constant.dart';
   import 'package:analyzer/src/generated/engine.dart';
   import 'package:analyzer/src/generated/source.dart';
   import 'package:analyzer/src/generated/testing/ast_test_factory.dart';
  
positive.code: // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
  // 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:collection';
  
  import 'package:analyzer/dart/analysis/features.dart';
  import 'package:analyzer/dart/ast/ast.dart';
  
negative.code:           ClassElement definingClass, String? name,
            [List<DartType> argumentTypes = const []]) =>
        constructorElement(definingClass, name, false, argumentTypes);
  
    static ExportElementImpl exportFor(LibraryElement exportedLibrary,
        [List<NamespaceCombinator> combinators = const <NamespaceCombinator>[]]) {
  