def unpack(cls, msg, client, server, _):
        """Parse message and return an `OpKillCursors`.

        Takes the client message as bytes, the client and server socket objects,
        and the client request id.
        """
        # Leading 4 bytes are reserved.
        num_of_cursor_ids, = _UNPACK_INT(msg[4:8])
        cursor_ids = []
        pos = 8
        for _ in range(num_of_cursor_ids):
            cursor_ids.append(_UNPACK_INT(msg[pos:pos + 4])[0])
            pos += 4
        return OpKillCursors(_client=client, cursor_ids=cursor_ids,
                             _server=server)
Parse message and return an `OpKillCursors`.

        Takes the client message as bytes, the client and server socket objects,
        and the client request id.