IndicatorAreaEventArgs

 using cAlgo.API;
 namespace cAlgo
 {
     // This example shows how to use the IndicatorAreaEventArgs
     // IndicatorAreaEventArgs is the base class of IndicatorAreaAddedEventArgs and IndicatorAreaRemovedEventArgs
     [Indicator(IsOverlay = true, TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
     public class IndicatorAreaEventArgsSample : Indicator
     {
         protected override void Initialize()
         {
             Chart.IndicatorAreaAdded += Chart_IndicatorAreaAdded;
             Chart.IndicatorAreaRemoved += Chart_IndicatorAreaRemoved;
         }
         private void Chart_IndicatorAreaRemoved(IndicatorAreaRemovedEventArgs obj)
         {
             var indicatorAreaEventArgs = obj as IndicatorAreaEventArgs;
         }
         private void Chart_IndicatorAreaAdded(IndicatorAreaAddedEventArgs obj)
         {
             var indicatorAreaEventArgs = obj as IndicatorAreaEventArgs;
         }
         public override void Calculate(int index)
         {
         }
     }
 }

 import clr
 clr.AddReference("cAlgo.API")
 from cAlgo.API import *
 class Test():    
     def initialize(self):
         api.Chart.IndicatorAreaAdded += self.on_chart_indicator_area_added
         api.Chart.IndicatorAreaRemoved += self.on_chart_indicator_area_removed
     def on_chart_indicator_area_added(self, args):
         print(f"Indicator area added")
     def on_chart_indicator_area_removed(self, args):
         print(f"Indicator area removed")