# Insert `sibling` after `self`.
	fun insert_after(sibling: MdNode) do
		sibling.unlink
		sibling.next = next
		if sibling.next != null then
			sibling.next.as(not null).prev = sibling
		end
		sibling.prev = self
		next = sibling
		sibling.parent = parent
		if sibling.next == null then
			sibling.parent.as(not null).last_child = sibling
		end
	end