Eduardokum\LaravelBoleto\Util::fatorVencimentoBack PHP Method

    public static function fatorVencimentoBack($factor, $format = 'Y-m-d')
    {
        $date = Carbon::create(1997, 10, 7, 0, 0, 0)->addDay($factor);
        return $format ? $date->format($format) : $date;
    }