public function set($key, $value)
    {
        if (!$value instanceof Check) {
            throw new InvalidArgumentException('Element is not a check object.');
        }

        return parent::set($key, $value);
    }
public function set($key, $value)
    {
        if (!$value instanceof Check) {
            throw new InvalidArgumentException('Element is not a check object.');
        }

        return parent::set($key, $value);
    }
{@inheritDoc}