remove method

@override void remove(NopListenerHandle key)

Implementation

@override
void remove(NopListenerHandle key) {
  assert(!_dispose);
  assert(_handles.contains(key));
  _handles.remove(key);

  final local = data;
  if (local is Listenable) {
    local.removeListener(key.update);
  }
  onRemove();
}