code: private Variants parseDayPeriods(JsonObject calendar, String group) {
      JsonObject node = resolve(calendar, "dayPeriods", group);
  
      JsonObject abbr = resolve(node, "abbreviated");
      JsonObject narrow = resolve(node, "narrow");
      JsonObject wide = resolve(node, "wide");
  
      return new Variants(
          new String[] { string(abbr, "am"), string(abbr, "pm") },
          new String[] { string(narrow, "am"), string(narrow, "pm") },
          new String[] { },
          new String[] { string(wide, "am"), string(wide, "pm") });
    }
docs: Parse day period information (AM, PM).