:return: all knows locations

def get_locations():
        """
        :return: all knows locations
        """
        LOGGER.debug("LocationService.get_locations")
        args = {'http_operation': 'GET', 'operation_path': ''}
        response = LocationService.requester.call(args)
        ret = None
        if response.rc == 0:
            ret = []
            for location in response.response_content['locations']:
                ret.append(Location.json_2_location(location))
        else:
            err_msg = 'LocationService.get_locations - Problem while getting locations. ' \
                      'Reason: ' + str(response.response_content) + '-' + str(response.error_message) + \
                      " (" + str(response.rc) + ")"
            LOGGER.warning(err_msg)
        return ret