       if waiters[dep.id]
         index = _.indexOf(waiterObs, dep)
         flushWaiters(index)
+    undefined
 
   inTransaction = (event, context, f, args) ->
     if rootEvent

        sink event
    unsubAll = ->
      sub.unsub?() for sub in subscriptions
    subscribeInput = (subscription) ->
      subscription.unsub = (subscription.input.subscribeInternal(guardedSink(subscription.input)))
    unsubscribeInput = (input) ->

  flush = ->
    while waiterObs.length > 0
      flushWaiters(0)
    undefined

  flushWaiters = (index) ->
    obs = waiterObs[index]
