unlisten method

void unlisten(dynamic callback(ValueUpdate update))

Implementation

void unlisten(Function(ValueUpdate update) callback) {
  if (callbacks.containsKey(callback)) {
    var cacheLevel = callbacks.remove(callback);
    if (callbacks.isEmpty) {
      requester._subscription.removeSubscription(this);
    } else if (cacheLevel == currentQos && currentQos > 1) {
      updateQos();
    }
  }
}