class A<T> : A<T[]>, IEquatable<A<T>>
  {
    public bool Equals(A<T> a)
    {
      if (a == null) return false;
      return true;
    }

    public override bool Equals(object obj)
    {
      if (ReferenceEquals(this, obj)) return true;
      return Equals(obj as A<T>);
    }

    public override int GetHashCode()
    {
      return 0;
    } // Press Alt+Ins
  }