How to use the pyhik.constants.DEFAULT_HEADERS function in pyHik

self.usr = usr
        self.pwd = pwd
        self.cam_id = 0
        self.name = ''
        self.device_type = None
        self.motion_detection = None
        self._motion_detection_xml = None

        self.root_url = '{}:{}'.format(host, port)

        # Build requests session for main thread calls
        # Default to basic authentication. It will change to digest inside
        # get_device_info if basic fails
        self.hik_request = requests.Session()
        self.hik_request.auth = (usr, pwd)
        self.hik_request.headers.update(DEFAULT_HEADERS)

        # Define event stream processing thread
        self.kill_thrd = threading.Event()
        self.reset_thrd = threading.Event()
        self.thrd = threading.Thread(
            target=self.alert_stream, args=(self.reset_thrd, self.kill_thrd,))
        self.thrd.daemon = False

        # Callbacks
        self._updateCallbacks = []

        self.initialize()