public static Task<Nullable<double>> SumAsync(
	this IMongoQueryable<Nullable<double>> source,
	CancellationToken cancellationToken = null
)

<ExtensionAttribute>
Public Shared Function SumAsync ( 
	source As IMongoQueryable(Of Nullable(Of Double)),
	Optional cancellationToken As CancellationToken = Nothing
) As Task(Of Nullable(Of Double))

[<ExtensionAttribute>]
static member SumAsync : 
        source : IMongoQueryable<Nullable<float>> * 
        ?cancellationToken : CancellationToken 
(* Defaults:
        let _cancellationToken = defaultArg cancellationToken null
*)
-> Task<Nullable<float>>