public async Task Subscribe(string code, string guid)
        {
            var senderId = _registrationCache.GetSenderId(guid);

            if (senderId != null)
            {
                if (!_lineNotifySubscription.IsRegistered(senderId))
                {
                    await _lineNotifySubscription.SaveToken(senderId, code);

                    _registrationCache.Remove(guid);;
                }
            }
        }