use std::collections::HashMap;

fn read_with_cache<'a>(
    storage: &HashMap<Vec<u8>, Vec<u8>>,
    cache: &'a mut HashMap<Vec<u8>, Vec<u8>>,
    key: &Vec<u8>,
) -> Option<&'a Vec<u8>> {

    if let Some(res) = cache.get(key) {
        return Some(res);
    }

    if let Some(data) = storage.get(key) {
        cache.insert(key.to_vec(), data.to_vec());
        return cache.get(key);
    }
    None
}

fn main() {

}