public function store($identifier)
    {
        $content = $this->getContent();

        if ($this->storedCartWithIdentifierExists($identifier)) {
            throw new CartAlreadyStoredException("A cart with identifier {$identifier} was already stored.");
        }

        $this->getConnection()->table($this->getTableName())->insert([
            'identifier' => $identifier,
            'instance' => $this->currentInstance(),
            'content' => serialize($content)
        ]);

        $this->events->fire('cart.stored');
    }