async def METHOD_NAME(self, params, callback, request_callback=None):
    self.logger.info("create subscription")
    result = ua.CreateSubscriptionResult()
    result.RevisedPublishingInterval = params.RequestedPublishingInterval
    result.RevisedLifetimeCount = params.RequestedLifetimeCount
    result.RevisedMaxKeepAliveCount = params.RequestedMaxKeepAliveCount
    self._sub_id_counter += 1
    result.SubscriptionId = self._sub_id_counter
    internal_sub = InternalSubscription(result, self.aspace, callback, request_callback=request_callback)
    await internal_sub.start()
    self.subscriptions[result.SubscriptionId] = internal_sub
    return result