public virtual void PrepareRequest(WebRequest request)
        {
            var info        = RequestInfo.FromVisit(CurrentRequest);
            var httpRequest = request as HttpWebRequest;

            if (httpRequest != null)
            {
                httpRequest.UserAgent = CurrentRequest.GetVariable("UserAgent", "Colossus");
                httpRequest.Referer   = CurrentRequest.GetVariable("Referrer", CurrentRequest.GetVariable("Referer", ""));
            }
            request.Headers.AddChunked(DataEncoding.RequestDataKey, DataEncoding.EncodeHeaderValue(info));
        }