How to use the fbtftp.base_server.ServerStats function in fbtftp

self._retries = retries
        self._timeout = timeout
        self._server_stats_callback = server_stats_callback
        # the format of the peer tuple is different for v4 and v6
        self._family = socket.AF_INET6
        if isinstance(
            ipaddress.ip_address(self._address), ipaddress.IPv4Address
        ):
            self._family = socket.AF_INET
        self._listener = socket.socket(self._family, socket.SOCK_DGRAM)
        self._listener.setblocking(0)  # non-blocking
        self._listener.bind((address, port))
        self._epoll = select.epoll()
        self._epoll.register(self._listener.fileno(), select.EPOLLIN)
        self._should_stop = False
        self._server_stats = ServerStats(address, stats_interval_seconds)
        self._metrics_timer = None

self._address = address
        self._port = port
        self._retries = retries
        self._timeout = timeout
        self._server_stats_callback = server_stats_callback
        # the format of the peer tuple is different for v4 and v6
        self._family = socket.AF_INET6
        if isinstance(ipaddress.ip_address(self._address), ipaddress.IPv4Address):
            self._family = socket.AF_INET
        self._listener = socket.socket(self._family, socket.SOCK_DGRAM)
        self._listener.setblocking(0)  # non-blocking
        self._listener.bind((address, port))
        self._epoll = select.epoll()
        self._epoll.register(self._listener.fileno(), select.EPOLLIN)
        self._should_stop = False
        self._server_stats = ServerStats(address, stats_interval_seconds)
        self._metrics_timer = None