public static function delete($id = null, $connection)
    {
        if (gettype($id)!="string" && !is_numeric($id)) {
            throw new ClusterpointException("\"->delete()\" function: \"_id\" is not in valid format.", 9002);
        }
        $connection->method = 'DELETE';
        $connection->action = '['.urlencode($id).']';
        return self::sendQuery($connection);
    }