public static UBinarySize? Sum<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, UBinarySize?> selector
)
<ExtensionAttribute>
Public Shared Function Sum(Of TSource) ( 
	source As IEnumerable(Of TSource),
	selector As Func(Of TSource, UBinarySize?)
) As UBinarySize?public:
[ExtensionAttribute]
generic<typename TSource>
static Nullable<UBinarySize> Sum(
	IEnumerable<TSource>^ source, 
	Func<TSource, Nullable<UBinarySize>>^ selector
)[<ExtensionAttribute>]
static member Sum : 
        source : IEnumerable<'TSource> * 
        selector : Func<'TSource, Nullable<UBinarySize>> -> Nullable<UBinarySize> Items in source that are are excluded from the computation of the sum. This method returns zero if source contains no elements or all elements are .
| ArgumentNullException | source or selector is . | 
| OverflowException | The sum is larger than UBinarySizeMaxValue. |