private function throttleUntil($attempts)
    {
        if ($attempts < 5) {
            return null;
        }
        $wait = pow(($attempts - 4), 2);

        return Carbon::create()->addSeconds($wait);
    }
private function throttleUntil($attempts)
    {
        if ($attempts < 5) {
            return null;
        }
        $wait = pow(($attempts - 4), 2);

        return Carbon::create()->addSeconds($wait);
    }
private function throttleUntil ( $ attempts ) { if ( $ attempts < 5 ) { return null ; } $ wait = pow ( ( $ attempts - 4 ) , 2 ) ; return Carbon :: create ( ) -> addSeconds ( $ wait ) ; }
Calculate the amount of time until we should throttle login attempts for
a user.

The amount is increased exponentially with each attempt: 1, 4, 9, 16, 25,
36… seconds.

Note: I just realized this is conceptually wrong: we should throttle
based on remote_addr, not username. So, this isn't used, yet.

@param int $attempts

@return \DateTime
Calculate the amount of time until we should throttle login attempts for a user .