def update(self, display_name=None, display_description=None):
        """
        Update the specified values on this snapshot. You may specify one or
        more values to update. If no values are specified as non-None, the call
        is a no-op; no exception will be raised.
        """
        return self.manager.update(self, display_name=display_name,
                display_description=display_description)