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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 _verify_sector_identifier(self, request):
 """ Verify `sector_identifier_uri` is reachable and that it contains `redirect_uri`s. :param request: Provider registration request :return: si_redirects, sector_id :raises: InvalidSectorIdentifier """

        si_url = request["sector_identifier_uri"]
        try:
            res = self.endpoint_context.httpc.get(si_url)
        except Exception as err:
            logger.error(err)
            res = None

        if not res:
            raise InvalidSectorIdentifier("Couldn't read from sector_identifier_uri")

        logger.debug("sector_identifier_uri => %s", sanitize(res.text))

        try:
            si_redirects = json.loads(res.text)
        except ValueError:
            raise InvalidSectorIdentifier(
                "Error deserializing sector_identifier_uri content")

        if "redirect_uris" in request:
            logger.debug("redirect_uris: %s", request["redirect_uris"])
            for uri in request["redirect_uris"]:
                if uri not in si_redirects:
                    raise InvalidSectorIdentifier(
                        "redirect_uri missing from sector_identifiers")

        return si_redirects, si_url