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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def refresh_toc(self, refresh_done_callback, toc_cache):
 """Start refreshing the table of loggale variables"""


        self._useV2 = self.cf.platform.get_protocol_version() >= 4

        self._toc_cache = toc_cache
        self._refresh_callback = refresh_done_callback
        self.toc = None

        pk = CRTPPacket()
        pk.set_header(CRTPPort.LOGGING, CHAN_SETTINGS)
        pk.data = (CMD_RESET_LOGGING,)
        self.cf.send_packet(pk, expected_reply=(CMD_RESET_LOGGING,))