class Frequency implements TemporalAmount, Serializable {

  public static Frequency ofDays(int days) {
    if (days % 7 == 0) {
      return ofWeeks(days / 7);
    }
    return new Frequency(Period.ofDays(days));
  }

  private  Frequency(Period period);
  private  Frequency(Period period, String name);

}