Object subscribe(void onNext(value), [ void onThrow(exception) = null, void onReturn() = null ])

Subscribe to the platform's popState events.

Source 

Object subscribe(void onNext(dynamic value),
    [void onThrow(dynamic exception) = null, void onReturn() = null]) {
  return this._subject.listen(onNext, onError: onThrow, onDone: onReturn);
}