/**
  * Unsubscribe from the post author or site.
  * @param boolean $notify
  * @return array
  */
 protected function unsubscribe($notify = true)
 {
     $prompt_post = new Prompt_Post($this->post_id);
     $prompt_author = new Prompt_User($prompt_post->get_wp_post()->post_author);
     if ($prompt_author->is_subscribed($this->user_id)) {
         $this->author_unsubscribe($prompt_author, $notify);
         return;
     }
     // The user was not subscribed to the post author, so unsubscribe them from the site.
     $prompt_site = new Prompt_Site();
     $prompt_site->unsubscribe($this->user_id);
     if ($notify) {
         Prompt_Subscription_Mailing::send_unsubscription_notification($this->user_id, $prompt_site);
     }
 }