# Unlink `self` from its `parent`
	fun unlink do
		if prev != null then
			prev.as(not null).next = next
		else if parent != null then
			parent.as(not null).first_child = next
		end
		if next != null then
			next.as(not null).prev = prev
		else if parent != null then
			parent.as(not null).last_child = prev
		end
		parent = null
		next = null
		prev = null
	end