/*
 * call-seq:
 *   attribute_with_ns(name, namespace)
 *
 * Get the attribute node with +name+ and +namespace+
 */
static VALUE attribute_with_ns(VALUE self, VALUE name, VALUE namespace)
{
  xmlNodePtr node;
  xmlAttrPtr prop;
  Data_Get_Struct(self, xmlNode, node);
  prop = xmlHasNsProp(node, (xmlChar *)StringValuePtr(name),
      NIL_P(namespace) ? NULL : (xmlChar *)StringValuePtr(namespace));

  if(! prop) return Qnil;
  return Nokogiri_wrap_xml_node(Qnil, (xmlNodePtr)prop);
}