public function increment($member, $increment = 1)
    {
        return $this->strToVal(
            $this->redis->zincrby($this->key, $this->valToStr($increment), $this->valToStr($member))
        );
    }
public function increment($member, $increment = 1)
    {
        return $this->strToVal(
            $this->redis->zincrby($this->key, $this->valToStr($increment), $this->valToStr($member))
        );
    }
@link https://redis.io/commands/zincrby

@param string|number $member    Score of $member will be incremented.
@param float|int     $increment Increment the score behind $member by this much.

@return number|string New score behind $member.