public static TResult Fold<T, TResult>(
	this IEnumerable<T> source,
	Func<T, T, T, TResult> folder
)

<ExtensionAttribute> _
Public Shared Function Fold(Of T, TResult) ( _
	source As IEnumerable(Of T), _
	folder As Func(Of T, T, T, TResult) _
) As TResult

public:
[ExtensionAttribute]
generic<typename T, typename TResult>
static TResult Fold(
	IEnumerable<T>^ source, 
	Func<T, T, T, TResult>^ folder
)