<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def unsubscribe(self, destination=None, id=None, headers=None, **keyword_headers):
 """ Unsubscribe from a destination by either id or the destination name. :param str destination: the name of the topic or queue to unsubscribe from :param str id: the unique identifier of the topic or queue to unsubscribe from :param dict headers: a map of any additional headers the broker requires :param keyword_headers: any additional headers the broker requires """

        assert id is not None or destination is not None, "'id' or 'destination' is required"
        headers = utils.merge_headers([headers, keyword_headers])
        if id:
            headers[HDR_ID] = id
        if destination:
            headers[HDR_DESTINATION] = destination
        self.send_frame(CMD_UNSUBSCRIBE, headers)