docs: public void add(int theField, int theValue) {
  		switch (theField) {
  		case Calendar.YEAR:
  			setValue(DateUtils.addYears(getValue(), theValue), getPrecision());
  			break;
  		case Calendar.MONTH:
  			setValue(DateUtils.addMonths(getValue(), theValue), getPrecision());
  			break;
  		case Calendar.DATE:
  			setValue(DateUtils.addDays(getValue(), theValue), getPrecision());
  			break;
  		case Calendar.HOUR:
  			setValue(DateUtils.addHours(getValue(), theValue), getPrecision());
  			break;
  		case Calendar.MINUTE:
  			setValue(DateUtils.addMinutes(getValue(), theValue), getPrecision());
  			break;
  		case Calendar.SECOND:
  			setValue(DateUtils.addSeconds(getValue(), theValue), getPrecision());
  			break;
  		case Calendar.MILLISECOND:
  			setValue(DateUtils.addMilliseconds(getValue(), theValue), getPrecision());
  			break;
  		default:
  			throw new IllegalArgumentException("Unknown field constant: " + theField);
  		}
  	}