dict: device uptime

def uptime(self):
        """dict: device uptime
        """
        namespace = 'urn:brocade.com:mgmt:brocade-system'
        get_system_uptime = ET.Element('get-system-uptime', xmlns=namespace)
        results = self._callback(get_system_uptime, handler='get')
        system_uptime = dict(days=results.find('.//{%s}days' % namespace).text,
                             hours=results.find('.//{%s}hours' %
                                                namespace).text,
                             minutes=results.find('.//{%s}minutes' %
                                                  namespace).text,
                             seconds=results.find('.//{%s}seconds' %
                                                  namespace).text)
        return system_uptime