public int virConnectUnregisterCloseCallback(virConnectCloseFunc cb)
 {
     return API.virConnectUnregisterCloseCallback(_ConnectPtr, cb);
 }
 public int virConnectRegisterCloseCallback(virConnectCloseFunc cb)
 {
     return API.virConnectRegisterCloseCallback(_ConnectPtr, cb, IntPtr.Zero, API._Dummy_virFreeCallback);
 }