code: public static boolean isValidRgroupQueryLabel(String Rxx) {
          Matcher matcher = validLabelPattern.matcher(Rxx);
          if (matcher.find()) {
              int groupNumber = Integer.valueOf(Rxx.substring(1));
              if (groupNumber >= 1 && groupNumber <= 32) {
                  return true;
              }
          }
          return false;
      }
docs: Validates a Pseudo atom's label to be valid RGroup query label (R1..R32).
  @param Rxx R-group label like R1 or R10
  @return true if R1..R32, otherwise false