public static Task<long> LongCountAsync<TSource>(
	this IQueryable<TSource> source,
	Expression<Func<TSource, bool>> predicate
)

<ExtensionAttribute>
Public Shared Function LongCountAsync(Of TSource) ( 
	source As IQueryable(Of TSource),
	predicate As Expression(Of Func(Of TSource, Boolean))
) As Task(Of Long)