(PHP 5, PHP 7)
DOMElement::setAttributeNS — Adds new attribute
$namespaceURI
   , string $qualifiedName
   , string $value
   )
   Sets an attribute with namespace namespaceURI and 
   name name to the given value. If the attribute 
   does not exist, it will be created.
  
namespaceURIThe namespace URI.
qualifiedNameThe qualified name of the attribute, as prefix:tagname.
valueThe value of the attribute.
No value is returned.
DOM_NO_MODIFICATION_ALLOWED_ERRRaised if the node is readonly.
DOM_NAMESPACE_ERR
       Raised if qualifiedName is a malformed qualified
       name, or if qualifiedName has a prefix and 
       namespaceURI is NULL.