level2

type Order struct {
	Price decimal.Decimal
	Size  decimal.Decimal
	Info  interface{}
}

type OrderBook struct {
	Sequence uint64             //Sequence || UpdateID
	Asks     *skiplist.SkipList //ask 是 要价，喊价 卖家 卖单 Sort price from low to high
	Bids     *skiplist.SkipList //bid 是 投标，买家 买单 Sort price from high to low
}