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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):
 """ Initiate a refresh of the parameter TOC. """

        self._useV2 = self.cf.platform.get_protocol_version() >= 4
        toc_fetcher = TocFetcher(self.cf, ParamTocElement,
                                 CRTPPort.PARAM, self.toc,
                                 refresh_done_callback, toc_cache)
        toc_fetcher.start()