Api\StructType\ApiExpiryDate::setMonth PHP 메소드

    public function setMonth($month = null)
    {
        // validation for constraint: string
        if (!is_null($month) && !is_string($month)) {
            throw new \InvalidArgumentException(sprintf('Invalid value, please provide a string, "%s" given', gettype($month)), __LINE__);
        }
        $this->month = $month;
        return $this;
    }