public async Task<RoutingInformation> RetrieveRouteAsync(RoutingRequest request)
        {
            var schnittstelle = new RoutingSchnittstelle();

            RoutingInformation response = await schnittstelle.GetRoutingAsync(request).ConfigureAwait(false);
            return response;
        }
        public static string Build(RoutingRequest request)
        {
            const string urlFormatString = BaseUrl +
                "type_origin=stopID&name_origin={0}&type_destination=stopID&name_destination={1}&ptOptionsActive=1&itOptionsActive=1" +
                "&itdDate={2:yyyyMMdd}&itdTime={2:HHmm}&routeType={3}" +
                "&outputFormat=JSON";

            // &itdTripDateTimeDepArr={4}

            var url = String.Format(urlFormatString, 
                request.FromStation, request.ToStation, 
                request.When, RouteTypeToQueryStringParameter(request.RouteType));

            return url;
        }