code: private void removeKey(Key k, List<Key>[] vector) {
      if (k == null) {
        throw new NullPointerException("Key can not be null");
      }
      if (vector == null) {
        throw new NullPointerException("ArrayList<Key>[] can not be null");
      }
  
      int[] h = hash.hash(k);
      hash.clear();
  
      for (int i = 0; i < nbHash; i++) {
        vector[h[i]].remove(k);
      }
    }
docs: Removes a given key from <i>this</i> filer.
  @param k The key to remove.
  @param vector The counting vector associated to the key.