code: func month2Period(month uint64) uint64 {
  	if month == 0 {
  		return 0
  	}
  
  	year := month / 12
  	if year < 70 {
  		year += 2000
  	} else if year < 100 {
  		year += 1900
  	}
  
  	return year*100 + month%12 + 1
  }
docs: // month2Period converts a month to a period.