code: public E set(int index, E element) {
      RangeCheck(index);
  
      E oldValue = (E) data[index];
      data[index] = element;
      return oldValue;
    }
docs: Replaces the element at the specified position in this list with
  the specified element.
  
  @param index   index of the element to replace
  @param element element to be stored at the specified position
  @return the element previously at the specified position
  @throws IndexOutOfBoundsException {@inheritDoc}