question: setitem sets this node 's item to `` item '' . if this node is invalid , throws an exception . performance : runs in o 1 time . concode_field_sep Object item concode_elem_sep List myList concode_field_sep ListNode next concode_elem_sep Object item concode_elem_sep ListNode prev concode_elem_sep boolean isValidNode concode_elem_sep void insertAfter concode_elem_sep void remove concode_elem_sep void insertBefore
target: void function ( Object arg0 ) { if ( ! isValidNode ( ) ) { throw new InvalidNodeException ( ) ; } this . item = arg0 ; }