public function debit($account, $amount, \DateTime $date)
    {
        $data = [
            $this->date,
            $account,
            $this->identity,
            null,
            $amount,
            $this->number,
            $date->format('Y-m-d'),
        ];

        if (false === fputcsv($this->handle, $data, ';', '"')) {
            throw new RuntimeException("Failed to write line.");
        }
    }