Parse a resource to get the first URN

        :param resource: XML Resource
        :type resource: etree._Element
        :return: Tuple representing previous and next urn
        :rtype: str

def firstUrn(resource):
        """ Parse a resource to get the first URN

        :param resource: XML Resource
        :type resource: etree._Element
        :return: Tuple representing previous and next urn
        :rtype: str
        """
        resource = xmlparser(resource)
        urn = resource.xpath("//ti:reply/ti:urn/text()", namespaces=XPATH_NAMESPACES, magic_string=True)

        if len(urn) > 0:
            urn = str(urn[0])
            return urn.split(":")[-1]