octal

    fn octal(buf: []u8, value: u64) error{OctalOverflow}!void {
        var remainder: u64 = value;
        var pos: usize = buf.len;
        while (remainder > 0 and pos > 0) {
            pos -= 1;
            const c: u8 = @as(u8, @intCast(remainder % 8)) + '0';
            buf[pos] = c;
            remainder /= 8;
            if (pos == 0 and remainder > 0) return error.OctalOverflow;
        }
    }