namespace System.Collections.Generic
{
    [DebuggerDisplay("Count = {Count}")]
    [DebuggerTypeProxy(typeof(ICollectionDebugView<?>))]
    public class HashSet<T> : ICollection<T>, IEnumerable, IEnumerable<T>, IReadOnlyCollection<T>, ISet<T>, IDeserializationCallback, ISerializable
    {
        public int EnsureCapacity(int capacity);
    }
}