CulturesViewModel - initialize a list of cultures to display in a tree-view

CulturesViewModel.cs

public class CulturesViewModel : INotifyPropertyChanged
{
    public CulturesViewModel() => SetupCultures();

    // ... INotifyPropertyChanged Implementation

    private void SetupCultures()
    {
        var cultureDataDict = CultureInfo.GetCultures(CultureTypes.AllCultures)
            .OrderBy(c => c.Name)
            .Select(c => new CultureData
            {
                CultureInfo = c,
                SubCultures = new List<CultureData>()
            })
            .ToDictionary(c => c.CultureInfo.Name);

        var rootCultures = new List<CultureData>();
        foreach (var cd in cultureDataDict.Values)
        {
            if (cd.CultureInfo.Parent.LCID == 0x7f)  // check for invariant culture
            {
                rootCultures.Add(cd);
            }
            else // add to parent culture
            {
                if (cultureDataDict.TryGetValue(cd.CultureInfo.Parent.Name, out CultureData parentCultureData))
                {
                    parentCultureData.SubCultures.Add(cd);
                }
                else
                {
                    throw new InvalidOperationException("parent culture not found");
                }
            }
        }

        foreach (var rootCulture in rootCultures.OrderBy(cd => cd.CultureInfo.EnglishName))
        {
            RootCultures.Add(rootCulture);
        }
    }

    public IList<CultureData> RootCultures { get; } = new List<CultureData>();

    private CultureData _selectedCulture;
    public CultureData SelectedCulture
    {
        get => _selectedCulture;
        set => SetProperty(ref _selectedCulture, value);
    }
}