Provided access to invoice id on manual subscription

Here is how i'm using it
$subscription = new Recurly_Subscription();
...
$subscription_response = $subscription->create();
$href = explode('/', $subscription_response->__get('invoice')->getHref());
$invoice_number= array_pop( $href );
Oh duh been in ruby land... no semicolon. Can you put it on one line please then.