public PlaceOrderRequest(string symbol, KunaOrderType type, decimal quantity, decimal?price, decimal?stopPrice)
 {
     Symbol    = symbol;
     Type      = type;
     Quantity  = quantity;
     StopPrice = stopPrice;
     Price     = price;
 }
 public PlaceOrderRequest(string symbol, KunaOrderSide side, KunaOrderType type, decimal quantity, decimal?price = null, decimal?stopPrice = null) : this(symbol, type, quantity, price, stopPrice)
 {
     Side = side;
 }