anchor.diff:    Token get beginToken => _returnType?.beginToken ?? functionKeyword;
   
     @override
  -  Iterable<SyntacticEntity> get childEntities => ChildEntities()
  -    ..add(_returnType)
  -    ..add(functionKeyword)
  -    ..add(_typeParameters)
  -    ..add(_parameters)
  -    ..add(question);
  -
  -  @override
     Token get endToken => question ?? _parameters.endToken;
   
     @override
  
positive.code:   set expression(Expression expression) {
      _expression = _becomeParentOf(expression as ExpressionImpl);
    }
  
    @override
    E? accept<E>(AstVisitor<E> visitor) =>
  
negative.code:   }
  
    @override
    Element? get declaredElement => name.staticElement;
  
    /// The type of function being defined by the alias.
  