/**
  * Import specific data: A single invoice
  *
  * @since  1.0.0
  * @param  object $obj The import object
  */
 protected function import_invoice($subscription, $obj)
 {
     $ms_invoice = MS_Model_Invoice::create_invoice($subscription);
     $ms_invoice->invoice_number = $obj->invoice_number;
     $ms_invoice->external_id = $obj->external_id;
     $ms_invoice->gateway_id = $obj->gateway;
     $ms_invoice->status = $obj->status;
     $ms_invoice->coupon_id = $obj->coupon;
     $ms_invoice->currency = $obj->currency;
     $ms_invoice->amount = $obj->amount;
     $ms_invoice->discount = $obj->discount;
     $ms_invoice->pro_rate = $obj->discount2;
     $ms_invoice->total = $obj->total;
     $ms_invoice->trial_period = $obj->for_trial;
     $ms_invoice->due_date = $obj->due;
     $ms_invoice->notes = $obj->notes;
     // Remember where this invoice comes from.
     $ms_invoice->source = $this->source_key;
     $ms_invoice->save();
 }