class Hamster::SortedSet::PlainAVLNode::Empty

def bulk_insert(items)
  items = items.to_a if !items.is_a?(Array)
  PlainAVLNode.from_items(items.sort)
end

def initialize;           end

def insert(item)
  PlainAVLNode.new(item, self, self)
end

def natural_order?; true; end