private Quantity SumReservedQuantity(IDemandOrProvider demandOrProvider)
 {
     if (demandOrProvider.GetNodeType().Equals(NodeType.Demand))
     {
         return(SumReservedQuantity(Demand.AsDemand(demandOrProvider)));
     }
     else
     {
         return(SumReservedQuantity(Provider.AsProvider(demandOrProvider)));
     }
 }