private static function tokenize($address)
    {
        $variants = array();

        foreach ($parts = explode(',', $address) as $first) {
            foreach ($parts as $second) {
                if ($second === $first) {
                    continue;
                }

                $variants[] = array('city' => $first, 'street' => $second);
            }
        }

        return $variants;
    }