anchor.diff:        var timer = subscription.timer;
         timer?.start();
         try {
  -        subscription.processor(node);
  +        node.accept(subscription.visitor);
         } catch (exception, stackTrace) {
           exceptionHandler(node, subscription.linter, exception, stackTrace);
         }
  
positive.code:   }
  }
  
  /// The container to register handlers for AST nodes.
  class NodeLintRegistry {
    final bool enableTiming;
    final List<_Subscription<AsExpression>> _forAsExpression = [];
  
negative.code: /// A single subscription for a node type, by the specified [linter].
  class _Subscription<T> {
    final LintRule linter;
    final AstVisitor visitor;
    final Stopwatch timer;
  
    _Subscription(this.linter, this.visitor, this.timer);
  }
  