public getElementsByTagNameNS(namespaceURI as String, localName as String) as DomNodeList throws DOMException:
Returns descendant elements matching a namespace URI and local name.
Matching elements as a DOM node list and Klyn list.
document = DOMParser().parseFromString("<root xmlns:x=\"urn:demo\"><x:item/></root>")
items = document.documentElement.getElementsByTagNameNS("urn:demo", "item")
print(items.length)