setChannel method
- StreamChannel<T> channel
Set a channel as the source and destination for channel.
A channel may be set at most once.
Either setChannel or setError may be called at most once. Trying to call either of them again will fail.
Implementation
void setChannel(StreamChannel<T> channel) {
  if (_set) throw StateError('The channel has already been set.');
  _set = true;
  _streamCompleter.setSourceStream(channel.stream);
  _sinkCompleter.setDestinationSink(channel.sink);
}