private function executionHandler(\stdClass $json)
    {
        return [
            "symbol" => $json->s,
            "side" => $json->S,
            "orderType" => $json->o,
            "quantity" => $json->q,
            "price" => $json->p,
            "executionType" => $json->x,
            "orderStatus" => $json->X,
            "rejectReason" => $json->r,
            "orderId" => $json->i,
            "clientOrderId" => $json->c,
            "orderTime" => $json->T,
            "eventTime" => $json->E,
        ];
    }