(PHP 5, PHP 7, PHP 8)
DOMElement::setAttributeNS — Adds new attribute
$namespace, string $qualifiedName, string $value): void
   Sets an attribute with namespace namespace and 
   name name to the given value. If the attribute 
   does not exist, it will be created.
  
namespaceThe namespace URI.
qualifiedName
       The qualified name of the attribute, as prefix:tagname.
      
valueThe value of the attribute.
没有返回值。
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 
       namespace is null.