private static void Download_Host(Session session, List <ObjectChange> changes)
        {
            Dictionary <XenRef <Host>, Host> records = Host.get_all_records(session);

            foreach (KeyValuePair <XenRef <Host>, Host> entry in records)
            {
                changes.Add(new ObjectChange(typeof(Host), entry.Key.opaque_ref, entry.Value));
            }
        }