code: func AdjustYear(y int64) (int64, error) {
  	y = int64(adjustYear(int(y)))
  	if y < int64(MinYear) || y > int64(MaxYear) {
  		return 0, errors.Trace(ErrInvalidYear)
  	}
  
  	return y, nil
  }
docs: // AdjustYear is used for adjusting year and checking its validation.