void UnsubscribeEvents(ITicker prev)
{
prev.OrderBook.OnChanged -= OnTickerOrderBookChanged;
prev.Changed -= OnTickerChanged;
prev.HistoryItemAdd -= OnTickerHistoryItemAdded;
prev.TradeHistoryAdd -= OnTickerTradeHistoryAdd;
prev.UnsubscribeOrderBookUpdates();
prev.UnsubscribeTickerUpdates();
prev.UnsubscribeTradeUpdates();
}