@Override
 public int parsePart(String value, EventRecurrence er) {
   Integer wkst = sParseWeekdayMap.get(value);
   if (wkst == null) {
     throw new InvalidFormatException("Invalid WKST value: " + value);
   }
   er.wkst = wkst;
   return PARSED_WKST;
 }