public SingleOrder this[Instrument instrument, string name]
 {
     get
     {
         NamedOrderTable namedOrderTable = this.orders[instrument] as NamedOrderTable;
         return(namedOrderTable[name]);
     }
 }
        public void Add(Instrument instrument, string name, SingleOrder order)
        {
            NamedOrderTable namedOrderTable;

            if (this.orders.ContainsKey(instrument))
            {
                namedOrderTable = (this.orders[instrument] as NamedOrderTable);
            }
            else
            {
                namedOrderTable = new NamedOrderTable();
                this.orders.Add(instrument, namedOrderTable);
            }
            namedOrderTable.Add(name, order);
        }