public function setVerticalAlign($verticalAlign) {
        if (!in_array($verticalAlign, [static::TOP, static::CENTER, static::BOTTOM], true)) {
            throw new \InvalidArgumentException(
                '$verticalAlign argument must be one of: ImagesGroupConfig::TOP, ImagesGroupConfig::CENTER, ImagesGroupConfig::BOTTOM'
            );
        }
        $this->verticalAlign = $verticalAlign;
        return $this;
    }