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
)