code: func ioOutputFormatTZOffset(ld *LineData, b *bytes.Buffer) error {
  	_, offset := ld.TimeStamp.Zone()
  	hour := offset / (60 * 60)
  	minute := (offset / 60) % 60
  	c := "-"
  	if hour >= 0 {
  		c = "+"
  	} else {
  		hour *= -1
  	}
  	_, err := b.WriteString(fmt.Sprintf("%s%02d%02d", c, hour, minute))
  	return err
  }
docs: // Formatting function used to implement the %tzoffset% code.