(PHP 5, PHP 7)
DOMNamedNodeMap::item — Retrieves a node specified by index
   Retrieves a node specified by index within the 
   DOMNamedNodeMap object.
  
indexIndex into this map.
   The node at the indexth position in the map, or NULL
   if that is not a valid index (greater than or equal to the number of nodes 
   in this map).