How to use the cflib.crtp.crtpstack.CRTPPort.PARAM function in cflib

def refresh_toc(self, refresh_done_callback, toc_cache):
        """
        Initiate a refresh of the parameter TOC.
        """
        self.toc = Toc()
        toc_fetcher = TocFetcher(self.cf, ParamTocElement,
                                CRTPPort.PARAM, self.toc,
                                refresh_done_callback, toc_cache)
        toc_fetcher.start()

def request_param_update(self, var_id):
        """Place a param update request on the queue"""
        pk = CRTPPacket()
        pk.set_header(CRTPPort.PARAM, READ_CHANNEL)
        pk.data = struct.pack('

def set_value(self, complete_name, value):
        """
        Set the value for the supplied parameter.
        """
        element = self.toc.get_element_by_complete_name(complete_name)

        if not element:
            logger.warning("Cannot set value for [%s], it's not in the TOC!",
                           complete_name)
        elif element.access == ParamTocElement.RO_ACCESS:
            logger.debug("[%s] is read only, no trying to set value", complete_name)
        else:
            varid = element.ident
            pk = CRTPPacket()
            pk.set_header(CRTPPort.PARAM, WRITE_CHANNEL)
            pk.data = struct.pack('

Set the value for the supplied parameter.
        """
        element = self.toc.get_element_by_complete_name(complete_name)

        if not element:
            logger.warning("Cannot set value for [%s], it's not in the TOC!",
                           complete_name)
            raise KeyError("{} not in param TOC".format(complete_name))
        elif element.access == ParamTocElement.RO_ACCESS:
            logger.debug("[%s] is read only, no trying to set value",
                         complete_name)
            raise AttributeError("{} is read-only!".format(complete_name))
        else:
            varid = element.ident
            pk = CRTPPacket()
            pk.set_header(CRTPPort.PARAM, WRITE_CHANNEL)
            pk.data = struct.pack('

def refresh_toc(self, refresh_done_callback, toc_cache):
        """
        Initiate a refresh of the parameter TOC.
        """
        toc_fetcher = TocFetcher(self.cf, ParamTocElement,
                                 CRTPPort.PARAM, self.toc,
                                 refresh_done_callback, toc_cache)
        toc_fetcher.start()

def __init__(self, cf, updated_callback):
        """Initialize the thread"""
        Thread.__init__(self)
        self.setDaemon(True)
        self.wait_lock = Lock()
        self.cf = cf
        self.updated_callback = updated_callback
        self.request_queue = Queue()
        self.cf.add_port_callback(CRTPPort.PARAM, self._new_packet_cb)
        self._should_close = False
        self._req_param = -1

def __init__(self, cf, updated_callback):
        """Initialize the thread"""
        Thread.__init__(self)
        self.setDaemon(True)
        self.wait_lock = Lock()
        self.cf = cf
        self.updated_callback = updated_callback
        self.request_queue = Queue()
        self.cf.add_port_callback(CRTPPort.PARAM, self._new_packet_cb)
        self._should_close = False
        self._req_param = -1

def request_param_update(self, var_id):
        """Place a param update request on the queue"""
        pk = CRTPPacket()
        pk.set_header(CRTPPort.PARAM, READ_CHANNEL)
        pk.data = struct.pack('