anchor.diff:  // 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 'package:analyzer/dart/analysis/features.dart';
  -import 'package:analyzer/dart/ast/precedence.dart';
   
   /// Defines the AST model. The AST (Abstract Syntax Tree) model describes the
   /// syntactic (as opposed to semantic) structure of Dart code. The semantic
  
positive.code:   /// is not a function-typed field formal parameter.
    FormalParameterList get parameters;
  
    /// If the parameter is function-typed, and has the question mark, then its
    /// function type is nullable. Having a nullable function type means that the
    /// parameter can be null.
    Token get question;
  
    /// Set the parameters of the function-typed parameter to the given
    /// [parameters].
    void set parameters(FormalParameterList parameters);
  
    /// Return the token representing the period.
    Token get period;
  
    /// Set the token representing the period to the given [token].
    void set period(Token token);
  
    /// Return the token representing the 'this' keyword.
    Token get thisKeyword;
  
negative.code: /// When an AST is resolved, the identifiers in the AST will be associated with
  /// the elements that they refer to and every expression in the AST will have a
  /// type associated with it.
  import 'package:analyzer/dart/analysis/features.dart';
  import 'package:analyzer/dart/ast/precedence.dart';
  import 'package:analyzer/dart/ast/syntactic_entity.dart';
  import 'package:analyzer/dart/ast/token.dart';
  import 'package:analyzer/dart/element/element.dart';
  