long rank;
 K key;
 V value;
 public Data(long rank, K key, V value){
   this.rank = rank;
   this.key=key;
   this.value=value;
 }
}

public class StandardCache<K, V extends Rankable> {

 /**
  * Constructor with a data source (assumed to be slow) and a cache size
  * @param ds the persistent layer of the the cache
  * @param capacity the number of entries that the cache can hold
  */
 public StandardCache(DataSource<K, V> ds, int capacity) {
   // Your code here
 }

 /**
  * Gets some data. If possible, retrieves it from cache to be fast. If the data is not cached,
  * retrieves it from the data source. If the cache is full, attempt to cache the returned data,
  * evicting the V with lowest rank among the ones that it has available
  * If there is a tie, the cache may choose any V with lowest rank to evict.
  * @param key the key of the cache entry being queried
  * @return the Rankable value of the cache entry
  */
 public V get(K key) {
   // Your code here
   
 }
 
}
 
 
/*
* For reference, relevant interfaces: Rankable and DataSource.
*/

public interface Rankable {
 /**
  * Returns the Rank of this object, using some algorithm and potentially
  * the internal state of the Rankable.
  */
 long getRank();
}

/*
* Remember that this is slow, relatively speaking
*/
public interface DataSource<K, V extends Rankable> {
 V get (K key);
}