src/BTR/RedisObjects/RedisSortedSet.php
public function rank($member, bool $reverse = false): ?int
    {
        if ($reverse) {
            return $this->redis->zrevrank($this->key, $this->valToStr($member));
        }

        return $this->redis->zrank($this->key, $this->valToStr($member));
    }
public function rank($member, bool $reverse = false): ?int
    {
        if ($reverse) {
            return $this->redis->zrevrank($this->key, $this->valToStr($member));
        }

        return $this->redis->zrank($this->key, $this->valToStr($member));
    }
@link https://redis.io/commands/zrank
@link https://redis.io/commands/zrevrank

@param string|number $member

@param bool          $reverse

@return int|null