SIL.Cog.Application.ViewModels.GlobalCorrespondencesViewModel.VarietiesChanged C# (CSharp) Method

        private void VarietiesChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            if (e.OldItems != null)
                _selectedVarieties.ExceptWith(e.OldItems.Cast<Variety>());
            if (e.NewItems != null)
                _selectedVarieties.UnionWith(e.NewItems.Cast<Variety>());
        }