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>
    {
        [DefaultMember("Item")]
        public sealed class Builder : ICollection<T>, IEnumerable, IEnumerable<T>, IList<T>, IReadOnlyCollection<T>, IReadOnlyList<T>, ICollection, IList
        {
            public int LastIndexOf(T item, int startIndex);
        }
    }
}