code: private static String arrayToString(int[] x) {
      StringBuilder sb = new StringBuilder("(");
      for (int j = 0; j < x.length; j++) {
        sb.append(x[j]);
        if (j != x.length - 1) {
          sb.append(", ");
        }
      }
      sb.append(")");
      return sb.toString();
    }
docs: end class TestSequenceModel