namespace System.Collections.Immutable { public sealed class ImmutableQueue<T> : IImmutableQueue<T>, IEnumerable<T>, IEnumerable { public struct Enumerator { public T Current { get; } public bool MoveNext(); } public bool IsEmpty { get; } public static ImmutableQueue<T> Empty { get; } public ImmutableQueue<T> Clear(); public T Peek(); public ImmutableQueue<T> Enqueue(T value); public ImmutableQueue<T> Dequeue(); public ImmutableQueue<T> Dequeue(out T value); public Enumerator GetEnumerator(); } }