code: void formatDayPeriod(StringBuilder b, ZonedDateTime d, int width, FieldVariants dayPeriods) {
      int hours = d.getHour();
      int index = hours < 12 ? 0 : 1;
      switch (width) {
        case 5:
          b.append(dayPeriods.narrow[index]);
          break;
  
        case 4:
          b.append(dayPeriods.wide[index]);
          break;
  
        case 3:
        case 2:
        case 1:
          b.append(dayPeriods.abbreviated[index]);
          break;
      }
    }
docs: Format the day period variant.