Task<GridFSDownloadStream<TFileId>> OpenDownloadStreamAsync(
	TFileId id,
	GridFSDownloadOptions options = null,
	CancellationToken cancellationToken = null
)

Function OpenDownloadStreamAsync ( 
	id As TFileId,
	Optional options As GridFSDownloadOptions = Nothing,
	Optional cancellationToken As CancellationToken = Nothing
) As Task(Of GridFSDownloadStream(Of TFileId))

abstract OpenDownloadStreamAsync : 
        id : 'TFileId * 
        ?options : GridFSDownloadOptions * 
        ?cancellationToken : CancellationToken 
(* Defaults:
        let _options = defaultArg options null
        let _cancellationToken = defaultArg cancellationToken null
*)
-> Task<GridFSDownloadStream<'TFileId>>