src/Ovh/Cdn/Cdn.php
public function orderCacheRule($nbCacheRule, $duration)
    {
        return json_decode(self::getClient()->orderCacheRule($this->sn, $nbCacheRule, $duration));
    }
public function orderCacheRule($nbCacheRule, $duration)
    {
        return json_decode(self::getClient()->orderCacheRule($this->sn, $nbCacheRule, $duration));
    }
Order cache rules and return a billing order object

@param int $nbCacheRule : number of backend needed
@param int $duration : durtaion (in month)
@return object billing order