docs: public static Days daysBetween(ReadablePartial start, ReadablePartial end) {
          if (start instanceof LocalDate && end instanceof LocalDate)   {
              Chronology chrono = DateTimeUtils.getChronology(start.getChronology());
              int days = chrono.days().getDifference(
                      ((LocalDate) end).getLocalMillis(), ((LocalDate) start).getLocalMillis());
              return Days.days(days);
          }
          int amount = BaseSingleFieldPeriod.between(start, end, ZERO);
          return Days.days(amount);
      }