code: Rule Time_HHMMSS() {
          return Sequence(
                  TwoDigits(),
                  FirstOf(
                          Sequence(
                                  TwoDigits(),
                                  FirstOf(TwoDigits(), push(0))
                          ),
                          pushAll(0, 0)
                  ),
                  EOI,
                  swap3() && push(convertToTime(popAsInt(), popAsInt(), popAsInt()))
          );
      }
docs: hh(mm(ss)?)?