library/Rediska/Key/List.php
public function shift()
    {
        $result = $this->_getRediskaOn()->shiftFromList($this->getName());

        if (!is_null($this->getExpire()) && $result) {
            $this->expire($this->getExpire(), $this->isExpireTimestamp());
        }

        return $result;
    }
public function shift()
    {
        $result = $this->_getRediskaOn()->shiftFromList($this->getName());

        if (!is_null($this->getExpire()) && $result) {
            $this->expire($this->getExpire(), $this->isExpireTimestamp());
        }

        return $result;
    }
Return and remove the first element of the List

@return mixed