public static DataFrame<long, string> Stack<R>(
	this DataFrame<R, string> frame,
	IEnumerable<string> idColumns,
	IEnumerable<string> valueColumns = null,
	string variableKey = "variable",
	string valueKey = "value"
)

<ExtensionAttribute>
Public Shared Function Stack(Of R) ( 
	frame As DataFrame(Of R, String),
	idColumns As IEnumerable(Of String),
	Optional valueColumns As IEnumerable(Of String) = Nothing,
	Optional variableKey As String = "variable",
	Optional valueKey As String = "value"
) As DataFrame(Of Long, String)

public:
[ExtensionAttribute]
generic<typename R>
static DataFrame<long long, String^>^ Stack(
	DataFrame<R, String^>^ frame, 
	IEnumerable<String^>^ idColumns, 
	IEnumerable<String^>^ valueColumns = nullptr, 
	String^ variableKey = L"variable", 
	String^ valueKey = L"value"
)

[<ExtensionAttribute>]
static member Stack : 
        frame : DataFrame<'R, string> * 
        idColumns : IEnumerable<string> * 
        ?valueColumns : IEnumerable<string> * 
        ?variableKey : string * 
        ?valueKey : string 
(* Defaults:
        let _valueColumns = defaultArg valueColumns null
        let _variableKey = defaultArg variableKey "variable"
        let _valueKey = defaultArg valueKey "value"
*)
-> DataFrame<int64, string>