public static IMultiQueryable<R1, R2, R3> Fork<T, R1, R2, R3>(
	this IQueryable<T> source,
	Expression<Func<T, ForkTuple<R1, R2, R3>>> mapper
)

<ExtensionAttribute> 
Public Shared Function Fork(Of T, R1, R2, R3) ( 
	source As IQueryable(Of T),
	mapper As Expression(Of Func(Of T, ForkTuple(Of R1, R2, R3)))
) As IMultiQueryable(Of R1, R2, R3)

public:
[ExtensionAttribute]
generic<typename T, typename R1, typename R2, typename R3>
static IMultiQueryable<R1, R2, R3>^ Fork(
	IQueryable<T>^ source, 
	Expression<Func<T, ForkTuple<R1, R2, R3>>^>^ mapper
)