Creates a StreamTransformer that delegates events to the given functions.
Example use of a duplicating transformer:
stringStream.transform(new StreamTransformer<String, String>.fromHandlers(
handleData: (String value, EventSink<String> sink) {
sink.add(value);
sink.add(value); // Duplicate the incoming events.
}));
Source
factory StreamTransformer.fromHandlers({
void handleData(S data, EventSink<T> sink),
void handleError(Object error, StackTrace stackTrace, EventSink<T> sink),
void handleDone(EventSink<T> sink)})
= _StreamHandlerTransformer<S, T>;