PendingOrderCancelledEventArgs

 using cAlgo.API;
 using cAlgo.API.Internals;
 namespace cAlgo.Robots;
 [Robot(AccessRights = AccessRights.None, AddIndicators = true)]
 public class Test : Robot
 {
     protected override void OnStart()
     {
         PendingOrders.Cancelled += OnPendingOrdersCancelled;
         var result = PlaceStopOrder(TradeType.Buy, Symbol.Name, 10000, Symbol.Ask + 10 * Symbol.PipSize);
         CancelPendingOrder(result.PendingOrder);
     }
     private void OnPendingOrdersCancelled(PendingOrderCancelledEventArgs args)
     {
         Print("Pending order with id {0} was cancelled. Reason: {1}", args.PendingOrder.Id, args.Reason);
     }
 }

 import clr
 clr.AddReference("cAlgo.API")
 # Import cAlgo API types
 from cAlgo.API import *
 # Import trading wrapper functions
 from robot_wrapper import *
 class Test():
     def on_start(self):
         api.PendingOrders.Cancelled += self.on_pending_orders_cancelled
         result = api.PlaceStopOrder(TradeType.Buy, api.Symbol.Name, 10000, api.Symbol.Ask + 10 * api.Symbol.PipSize)
         api.CancelPendingOrder(result.PendingOrder)
     def on_pending_orders_cancelled(self, args):
         print(f"Pending order with id {args.PendingOrder.Id} was cancelled. Reason: {args.Reason}")