code: def _get_music_services_data_xml(soco=None):
          
          device = soco or discovery.any_soco()
          log.debug("Fetching music services data from %s", device)
          available_services = device.musicServices.ListAvailableServices()
          descriptor_list_xml = available_services[
              'AvailableServiceDescriptorList']
          log.debug("Services descriptor list: %s", descriptor_list_xml)
          return descriptor_list_xml
docs: Fetch the music services data xml from a Sonos device.
  
          Args:
              soco (SoCo): a SoCo instance to query. If none is specified, a
              random device will be used. Defaults to `None`.
  
          Returns:
              str: a string containing the music services data xml