Returns an event that has been added to this server.
This method will return the first element in the first-in-first-out queue of events
that have been added to this instance. If no events are available, this Future
will
complete when the next event is added.
Source
Future<T> next() { if (_queue.isEmpty) { var c = new Completer<T>(); _completerQueue.add(c); return c.future; } var val = _queue.removeAt(0); return new Future.value(val); }