code: @Override
      public boolean delete(K key) throws Exception {
          if(key == null) {
              throw new NullPointerException("key");
          }
          
          return _store.delete(_keySerializer.serialize(key));
      }
docs: Deletes an object from the store based on its key.
  
  @param key
  the object key.
  @return true if the delete operation succeeds.
  @throws NullPointerException if <code>key</code> is null.
  @throws Exception if this operation cannot be completed successfully.