namespace System.Collections.Immutable
{
    [DefaultMember("Item")]
    public sealed class ImmutableList<T> : ICollection<T>, IEnumerable, IEnumerable<T>, IList<T>, IReadOnlyCollection<T>, IReadOnlyList<T>, ICollection, IList, IImmutableList<T>
    {
        public ImmutableList<T>! Sort(int index, int count, IComparer<T>? comparer);
    }
}