public static function call($method, $params = [])
        {
                static $ratecontrol;
                if(isset($ratecontrol))
                {
                        $delta = 500e3 - 1000e3*(microtime(true) - $ratecontrol);
                        if ($delta > 0) usleep($delta);
                }
                $ratecontrol = microtime(true);
                return parent::call($method, $params);
        }