removeListener method
Implementation
removeListener(OnChangeCallback callback) {
if (listeners != null) {
if (listeners!.contains(callback)) listeners!.remove(callback);
if (listeners!.isEmpty) listeners = null;
}
}
removeListener(OnChangeCallback callback) {
if (listeners != null) {
if (listeners!.contains(callback)) listeners!.remove(callback);
if (listeners!.isEmpty) listeners = null;
}
}