code: @Override
      public long toEpochDay() {
          long year = (long) prolepticYear;
          long julianEpochDay = ((year - 1) * 365) + Math.floorDiv((year - 1), 4) + (getDayOfYear() - 1);
          return julianEpochDay - JULIAN_0001_TO_ISO_1970;
      }
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