class Factory(object): def create(self, namespace): raise NotImplementedError() class Provider(object): def set(self, namespace, option, value): raise NotImplementedError() def get(self, namespace, option, default=None): raise NotImplementedError() def unset(self, namespace, option): raise NotImplementedError() def clear(self): raise NotImplementedError() def load(self): raise NotImplementedError() def save(self): raise NotImplementedError()