namespace System.Collections.Immutable
{
    [CollectionBuilder(typeof(ImmutableList), "Create")]
    [DefaultMember("Item")]
    public sealed class ImmutableList<T> : ICollection<T>, IEnumerable, IEnumerable<T>, IList<T>, IReadOnlyCollection<T>, IReadOnlyList<T>, ICollection, IList, IImmutableList<T>
    {
        public int LastIndexOf(T item, int index, int count, IEqualityComparer<T>? equalityComparer);
    }
}