nette latte authorization

MyPresenter.php
----------

/**
 * Handle action, only valid for a logged-in user otherwise throws
 * @User
 */
public function handleLike($itemId) { ... }



page.latte without auth testing
----------

<a n:href="like! $item->id">Like</a>




Task:
You want to hide the link, if the user is not authorized to perform such signal/action. How would you do that?
What would happen, if you decide to change the rules for signal handler (e.g. only allowed for users with an editor role)?