public IObservable <Trade> Trades(Action <ITradeConfigurator> configure)
        {
            var c = new TradeConfigurator(_trades);

            configure(c);
            return(c.Build());
        }
        public IObservable<Trade> Trades(Action<ITradeConfigurator> configure) {
            var c = new TradeConfigurator(_trades);
            configure(c);

            return c.Build();
        }