update method
Implementation
bool update(MaterialState state, {required bool value}) {
final result = value ? _states.add(state) : _states.remove(state);
if (result) for (final notify in _observers) notify();
return result;
}
bool update(MaterialState state, {required bool value}) {
final result = value ? _states.add(state) : _states.remove(state);
if (result) for (final notify in _observers) notify();
return result;
}