namespace System.Collections.Immutable
{
    [DebuggerDisplay("Count = {Count}")]
    [DebuggerTypeProxy(typeof(ImmutableEnumerableDebuggerProxy<?>))]
    [DefaultMember("Item")]
    public sealed class ImmutableList<T> : ICollection<T>, IEnumerable<T>, IList<T>, IReadOnlyCollection<T>, IReadOnlyList<T>, ICollection, IEnumerable, IList, IImmutableList<T>
    {
        public int FindIndex(Predicate<T>! match);
    }
}