Jbe.NewsReader.Domain.Feed.ItemsCollectionChanged C# (CSharp) Метод

        private void ItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            foreach (var item in e.OldItems?.Cast<FeedItem>() ?? Enumerable.Empty<FeedItem>())
            {
                item.PropertyChanged -= FeedItemPropertyChanged;
            }
            foreach (var item in e.NewItems?.Cast<FeedItem>() ?? Enumerable.Empty<FeedItem>())
            {
                item.PropertyChanged += FeedItemPropertyChanged;
            }
            UpdateUnreadItemsCount();
        }