'Override this method to implement a real asynchronous call rpc.
Returns:
True if the async call was completed successfully.'

def _WaitImpl(self):

    try:
        self.stub.MakeSyncCall(self.package, self.call, self.request, self.response)
    except Exception:
        (_, self._exception, self._traceback) = sys.exc_info()
    finally:
        self._state = RPC.FINISHING
        self._Callback()
    return True
