public async Task UpdateHolderInfo(string holderCode)
        {
            var request = WebRequest.Create(_baseUrl);

            request.Method = "POST";
            using (Stream requestStream = request.GetRequestStream())
            {
                var holderRequest = new HolderRequest()
                {
                    EquipmentSn   = holderCode,
                    DeviceType    = "8",
                    DeviceVersion = "1",
                    SessionId     = "94868768687778",
                    PackageType   = "175"
                };
                var holderRequestString = JsonConvert.SerializeObject(holderRequest);
                var holderRequestBuf    = Encoding.UTF8.GetBytes(holderRequestString);
                requestStream.Write(holderRequestBuf);
            }

            var response = await request.GetResponseAsync();

            string responceString = "";

            using (Stream dataStream = response.GetResponseStream())
            {
                StreamReader reader = new StreamReader(dataStream);
                responceString = await reader.ReadToEndAsync();
            }
        }
        private async Task <bool> PrvidePowerBank(HolderModel holderModel, PowerbankModel powerbank)
        {
            var request = WebRequest.Create(_baseUrl);

            request.Method = "POST";
            using (Stream requestStream = request.GetRequestStream())
            {
                var holderRequest = new HolderRequest()
                {
                    Position      = powerbank.Position.ToString(),
                    EquipmentSn   = holderModel.Code,
                    DeviceType    = "8",
                    DeviceVersion = "1",
                    SessionId     = "94868768687778",
                    PackageType   = "171"
                };
                var holderRequestString = JsonConvert.SerializeObject(holderRequest);
                var holderRequestBuf    = Encoding.UTF8.GetBytes(holderRequestString);
                requestStream.Write(holderRequestBuf);
            }

            var response = await request.GetResponseAsync();

            string responceString = "";

            using (Stream dataStream = response.GetResponseStream())
            {
                StreamReader reader = new StreamReader(dataStream);
                responceString = await reader.ReadToEndAsync();
            }
            return(true);
        }