public function IsSubscribed()
 {
     $forum_id = $this->owner->ID;
     $member_id = Member::currentUserID();
     return Forum_Subscribers::already_subscribed($forum_id, $member_id);
 }
 public function IsSubscribed($forum_id, $member_id)
 {
     $forum = Forum_Subscribers::get()->filter(array('MemberID' => $member_id, 'ForumID' => $forum_id))->First();
     if ($forum) {
         return true;
     } else {
         return false;
     }
 }