anchor.diff:   */
   abstract class ErrorCode {
     /**
  -   * Engine error code values.
  -   */
  -  @deprecated
  -  static const List<ErrorCode> values = errorCodeValues;
  -
  -  /**
  -   * An empty list of error codes.
  -   */
  -  @deprecated
  -  static const List<ErrorCode> EMPTY_LIST = const <ErrorCode>[];
  -
  -  /**
      * The name of the error code.
      */
     final String name;
  
positive.code: // Copyright (c) 2016, 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 'package:analyzer/error/error.dart'
      show errorCodeValues, errorCodeByUniqueName;
  
  /**
   * An error code associated with an [AnalysisError].
  
negative.code: 
    @override
    String toString() => uniqueName;
  }
  
  /**
  