code: void formatDayOfYear(StringBuilder b, ZonedDateTime d, int width) {
      int day = d.getDayOfYear();
      int digits = day < 10 ? 1 : day < 100 ? 2 : 3;
      switch (digits) {
        case 1:
          if (width > 1) {
            b.append('0');
          }
          // fall through
  
        case 2:
          if (width > 2) {
            b.append('0');
          }
          // fall through
  
        case 3:
          b.append(day);
          break;
      }
    }
docs: Format the 3-digit day of the year, zero padded.