Function restore_reactive_index 

pub fn restore_reactive_index<K, S, V>(
    state: ReactiveIndexRestoreState<K, S, V>,
    options: ReactiveIndexOptions,
) -> StorageResult<ReactiveIndex<K, S, V>>
where
    K: Clone + Ord + Debug + 'static,
    S: Clone + Ord + 'static,
    V: Clone + 'static,

Creates or computes restore_reactive_index.