glog.go
func (buf *buffer) twoDigits(i, d int) {
	buf.tmp[i+1] = digits[d%10]
	d /= 10
	buf.tmp[i] = digits[d%10]
}
func (buf *buffer) twoDigits(i, d int) {
	buf.tmp[i+1] = digits[d%10]
	d /= 10
	buf.tmp[i] = digits[d%10]
}
// twoDigits formats a zero-prefixed two-digit integer at buf.tmp[i].