code: func (c Calendar) formatDateTimeComponentDayOfWeek(datetime time.Time, length int) (string, error) {
  	switch length {
  	case datetimeFormatLength1Plus:
  		return c.formatDateTimeComponentDayOfWeekWide(datetime.Weekday()), nil
  	case datetimeFormatLength2Plus:
  		return c.formatDateTimeComponentDayOfWeekShort(datetime.Weekday()), nil
  	case datetimeFormatLengthAbbreviated:
  		return c.formatDateTimeComponentDayOfWeekAbbreviated(datetime.Weekday()), nil
  	case datetimeFormatLengthWide:
  		return c.formatDateTimeComponentDayOfWeekWide(datetime.Weekday()), nil
  	case datetimeFormatLengthNarrow:
  		return c.formatDateTimeComponentDayOfWeekNarrow(datetime.Weekday()), nil
  	}
  
  	return "", fmt.Errorf("unsupported year day-of-week: %d", length)
  }
docs: // formatDateTimeComponentDayOfWeek renders a day-of-week component.