public static IEnumerable<TSource> ExceptBy<TSource, TKey>(
	this IEnumerable<TSource> first,
	IEnumerable<TSource> second,
	Func<TSource, TKey> keySelector,
	IEqualityComparer<TKey> keyComparer
)

<ExtensionAttribute>
Public Shared Function ExceptBy(Of TSource, TKey) ( 
	first As IEnumerable(Of TSource),
	second As IEnumerable(Of TSource),
	keySelector As Func(Of TSource, TKey),
	keyComparer As IEqualityComparer(Of TKey)
) As IEnumerable(Of TSource)

public:
[ExtensionAttribute]
generic<typename TSource, typename TKey>
static IEnumerable<TSource>^ ExceptBy(
	IEnumerable<TSource>^ first, 
	IEnumerable<TSource>^ second, 
	Func<TSource, TKey>^ keySelector, 
	IEqualityComparer<TKey>^ keyComparer
)

[<ExtensionAttribute>]
static member ExceptBy : 
        first : IEnumerable<'TSource> * 
        second : IEnumerable<'TSource> * 
        keySelector : Func<'TSource, 'TKey> * 
        keyComparer : IEqualityComparer<'TKey> -> IEnumerable<'TSource>