close method
void
close()
closes the progress.
Implementation
void close() {
// /// If the stream is never wired
// /// then we have never listened to the stream.
// /// [devNull] is an example of a Progress that never
// /// wires the stream.
// /// In which case we won't get a done event so the
// /// completers won't complete.
// /// So we force them to here.
// if (!_wired) {
// _stdoutCompleter.complete(true);
// _stderrCompleter.complete(true);
// }
unawaited(_stderrController.close());
unawaited(_stdoutController.close());
_closed = true;
}