https://learn.microsoft.com/en-us/dotnet/api/system.collections.objectmodel.collection-1.setitem?view=netframework-4.8.1
CollectionT.SetItem(Int32, T) Method (System.Collections.ObjectModel) | Microsoft Learn
Replaces the element at the specified index.
methodsystemcollectionsmicrosoftlearn
https://learn.microsoft.com/en-us/dotnet/api/system.collections.objectmodel.collection-1.clearitems?view=netframework-4.8.1&redirectedfrom=MSDN
CollectionT.ClearItems Method (System.Collections.ObjectModel) | Microsoft Learn
methodsystemcollectionsmicrosoftlearn