private static void DuplexSample(List <string> l)
        {
            //"INSERT INTO UneseneVrednosti " +
            //"(IDGeoPodrucja, VremeMerenja, Vrednost) " +
            //"VALUES ('" + idGeoPodrucja + "', '" + datum + "', " + _unesenaPotrosnja + ")";

            var binding = new NetTcpBinding();
            var address = new EndpointAddress("net.tcp://localhost:10102/IInsert");

            var clientCallback = new UpisiCallback1();
            var context        = new InstanceContext(clientCallback);

            var factory = new DuplexChannelFactory <IInsert>(clientCallback, binding, address);

            IInsert messageChanel = factory.CreateChannel();

            //foreach (var item in l)
            //{
            Task.Run(() => messageChanel.InsertInto(l));
            // }
        }