code: public void setValue(int n, ValueType value) {
          if (VERIFY_INTEGRITY && value == null) {
              throw new IllegalArgumentException();
          }
          if (!isValid()) {
              throw new IllegalStateException("accessing top or bottom frame");
          }
          slotList.set(n, value);
      }
docs: Set the value at the <i>n</i>th slot.
  
  @param n
  the slot in which to set a new value
  @param value
  the value to set