public static function byId($ids, EarthIT_Schema_ResourceClass $rc)
 {
     if ($ids === '') {
         $ids = array();
     }
     if (is_scalar($ids)) {
         $ids = array($ids);
     }
     if (!is_array($ids)) {
         throw new Exception("'\$ids' parameter must be a scalar or array.  Got: " . var_export($ids, true));
     }
     // TODO: If just a single ID field, use an IN (...) instead
     $filters = array();
     foreach ($ids as $id) {
         $filters[] = self::exactFieldValues(EarthIT_Storage_Util::itemIdToFieldValues($id, $rc), $rc);
     }
     // It can be any of those IDs!
     return self::ored($filters);
 }