class UpTime {

    private UpTime() {
    }

    /**
     * Parses the first value in {@code /proc/uptime} for seconds since boot
     *
     * @return Seconds since boot
     */
    public static double getSystemUptimeSeconds() {<FILL_FUNCTION_BODY>}
}

        String uptime = FileUtil.getStringFromFile(ProcPath.UPTIME);
        int spaceIndex = uptime.indexOf(' ');
        if (spaceIndex < 0) {
            // No space, error
            return 0d;
        }
        return ParseUtil.parseDoubleOrDefault(uptime.substring(0, spaceIndex), 0d);
    
<no_super_class>