public function mapLinkTypeCodeToLinkTypeId($linkTypeCode)
    {

        // query weather or not the link type code has been mapped
        if (isset($this->linkTypes[$linkTypeCode])) {
            return $this->linkTypes[$linkTypeCode][MemberNames::LINK_TYPE_ID];
        }

        // throw an exception if the link type code has not been mapped yet
        throw new MapLinkTypeCodeToIdException(
            $this->appendExceptionSuffix(
                sprintf('Found not mapped link type code %s', $linkTypeCode)
            )
        );
    }