(PHP 5 >= 5.3.0)
SplDoublyLinkedList::offsetSet — Sets the value at the specified $index to $newval
   Sets the value at the specified index to newval.
  
indexThe index being set.
newval
       The new value for the index.
      
No value is returned.
   Throws OutOfRangeException when index is out of bounds or when index cannot be parsed as an integer.