XmlStreamWriter.attributeNS

void attributeNS(string namespaceUri, string local, string prefix, string value) @safe

Writes a namespace-qualified attribute.

`namespaceUri`	Namespace URI (empty means no namespace).
`local`	Local name.
`prefix`	Prefix to use (required when `namespaceUri` is non-empty).
`value`	Attribute value.