     }.name("mergeInner")
 }
 
-public func concatInner<T>(upstream: Stream<Stream<T>>) -> Stream<T>
+public func concatInner<T>(_ upstream: Stream<Stream<T>>) -> Stream<T>
 {
     return Stream<T> { progress, fulfill, reject, configure in
         

/// - Experiment: async + backpressure using blocking semaphore
///
public func asyncBackpressureBlock<T>(
    queue: DispatchQueue,
    high highCountForPause: Int,
    low lowCountForResume: Int
) -> (upstream: Stream<T>) -> Stream<T>

///
/// - e.g. `let mergedStream = [stream1, stream2, ...] |> mergeInner`
///
public func mergeInner<T>(_ upstream: Stream<Stream<T>>) -> Stream<T>
{
    return Stream<T> { progress, fulfill, reject, configure in
        
