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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 get_flag_record(self, feature_key: str) -> str: """Get feature flag record from redis. :param feature_key: key for feature flag :return: value of feature flag key in redis. :raises: KeyError if key is not found. """

        key_name = self._format_key_name()
        flag = self.redis.hget(key_name, feature_key)

        if flag is None:
            raise KeyError('Redis key: {0} not found.'.format(key_name))

        return flag