/**
  * Check if $user is subscribed to given $object
  *
  * @param User $user
  * @param ProjectObject $object
  * @param boolean $use_cache
  * @return boolean
  */
 function isSubscribed($user, $object, $use_cache = true)
 {
     if ($use_cache) {
         $cache_value = cache_get('user_subscriptions_' . $user->getId());
         if (is_array($cache_value)) {
             return in_array($object->getId(), $cache_value);
         } else {
             $cache_value = Subscriptions::rebuildUserCache($user);
             return in_array($object->getId(), $cache_value);
         }
         // if
     } else {
         return (bool) Subscriptions::count(array('user_id = ? AND parent_id = ?', $user->getId(), $object->getId()));
     }
     // if
 }