next method
Pass a value to the observer.
Implementation
@override
void next(T value) {
  DisposedError.checkNotDisposed(this);
  if (_hasStopped) return;
  for (final observer in [..._observers]) {
    observer.next(value);
  }
}
Pass a value to the observer.
@override
void next(T value) {
  DisposedError.checkNotDisposed(this);
  if (_hasStopped) return;
  for (final observer in [..._observers]) {
    observer.next(value);
  }
}