public function sendInvite($customerId, CustomerInvite $invite = null)
    {
        $data = is_null($invite) ? array() : $invite->exportData();
        $endpoint = '/admin/customers/'.$customerId.'/send_invite.json';
        $response = $this->request(
            $endpoint, 'POST', array(
            'custom_invite' => $data
            )
        );
        return $response['customer_invite'];
    }