dispose method
void
dispose()
Releases all listeners. After this call the notifier should not be used.
Implementation
void dispose() {
throwIfDisposed();
if (_notificationDepth > 0) {
throw StateError(
'dispose() cannot be called while notifyListeners() is running.',
);
}
_isDisposed = true;
_listeners.clear();
_listenerCount = 0;
_needsCompaction = false;
}