A read-only list of elements for traversal purposes.
Changes to the document from which this list was generated
are not reflected in this list. Changes to the individual
Element objects in the list are reflected.
Returns the indexth element in the list.
The first element has index 0. The last element
has index size()-1.
Parameters: index - the element to return the element at the specified position throws: IndexOutOfBoundsException - if index is negative or greater than or equal to the size of the list