public function setContacts($domainName, $contacts)
    {
        foreach ($contacts as $contact) {
            if (!$contact instanceof \Transip\Model\WhoisContact) {
                throw new \RuntimeException(sprintf('Contact is not an instance of %s', '\\Transip\\Model\\WhoisContact'));
            }
        }

        return $this->getSoapClient(array_merge(array($domainName, $contacts), array('__method' => 'setContacts')))->setContacts($domainName, $contacts);
    }