class Gapic::LruHash

def put key, value
  if @cache.key? key
    node = @cache[key]
    node.value = value
    move_to_top node
  else
    remove_tail if @cache.size >= @size
    new_node = Node.new key, value
    insert_at_top new_node
    @cache[key] = new_node
  end
end