public override T this[
	int i0,
	Nullable<long> hashVal = null
] { get; set; }

Public Overrides Default Property Item ( 
	i0 As Integer,
	Optional hashVal As Nullable(Of Long) = Nothing
) As T
	Get
	Set

public:
virtual property T default[int i0, Nullable<long long> hashVal = nullptr] {
	T get (int i0, Nullable<long long> hashVal = nullptr) override;
	void set (int i0, Nullable<long long> hashVal = nullptr, T value) override;
}

abstract Item : 'T with get, set
override Item : 'T with get, set