// retoor <retoor@molodetz.nl>
import "html" for Document
var doc = Document.parse("<div id='container'><span id='ref'>Reference</span></div>")
var container = doc.getElementById("container")
var ref = doc.getElementById("ref")
var p = doc.createElement("p")
p.textContent = "Before"
container.insertBefore(p, ref)
System.print(container.children.count) // expect: 2
System.print(container.firstChild.tagName) // expect: P
System.print(container.firstChild.textContent) // expect: Before
System.print(container.lastChild.tagName) // expect: SPAN
var a = doc.createElement("a")
a.textContent = "Link"
container.insertBefore(a, ref)
System.print(container.children.count) // expect: 3
System.print(container.children[1].tagName) // expect: A