docs: public IonValue systemGet(int index) throws IndexOutOfBoundsException
      {
          ListIterator<IonValue> iterator = systemIterator();
          IonValue value = null;
  
          if (index < 0) {
              throw new IndexOutOfBoundsException(""+index);
          }
  
          int ii;
          for (ii=0; ii<=index; ii++) {
              if (!iterator.hasNext()) {
                  throw new IndexOutOfBoundsException(""+index);
              }
              value = iterator.next();
          }
          return value;
      }