[API] update customers billingshipping address: country?

Hello,
I am developing a custom integration for LS eCom with the PHP client. I am syncing a local copy of customers and countries (mysql) periodically to cache them.
When POSTing or PUTing a customer object using the API (https://developers.lightspeedhq.com/ecom/endpoints/customer/), how do we make sure the country selection for the billing/shipping address is persisted? I see the region as an option (addressBillingRegion), but not the country.
I'm assuming along the lines of:
{
id:123456,
'addressBillingCountry' =>
array(4) {
'id' => string(3) "150"
'code' =>
string(2) "nl"
'code3' =>
string(3) "nld"
'title' =>
string(16) "Netherlands, The"
}
}