public function getBeaconsUnique($token, $event, array $dates)
    {
        $keys = [];

        foreach ($dates as $date) {
            $keys[] = $this->generateEntryKey(
                    $token,
                    $event,
                    $date
                ) . '_unique';
        }

        return (int)
        $this->doRedisQuery(function () use ($keys) {
            $this
                ->redis
                ->pfCount($keys);
        }, 0);
    }