r the method will be called asynchrounsouly.
        :param error_handler: Errback function. In case of an error the given
            callback gets the corresponding exception instance.
        :param defer: Run the method asynchrounsly and return a defer.Deferred.
            This options is only available as a keyword.

        :raises: dbus.DBusException

        :returns: An AptTransaction instance.
        Z