code: public V get(K key)
    {
      Entry<V> entry = _cache.get(key);
  
      if (entry == null)
        return null;
  
      if (entry.isValid())
        return entry.getValue();
      else {
        _cache.remove(key);
  
        return null;
      }
    }
docs: Gets an item from the cache, returning null if expired.