code: @SuppressWarnings("unchecked")
  	@Override
  	public V put(Pair<T, I> key, V value) {
  		boolean isNew = keys.add(key);
  		int index = keys.indexOf(key);
  		Object old = null;
  		if (isNew)
  			values.add(index, value);
  		else
  			old = values.set(index, value);
  		return (V) old;
  	}
docs: {@inheritDoc}