code: def to_hostnames_list(ref, tab):  # pragma: no cover, to be deprecated?
      
      res = []
      for host in tab:
          if hasattr(host, 'host_name'):
              res.append(host.host_name)
      return res
docs: Convert Host list into a list of  host_name
  
      :param ref: Not used
      :type ref:
      :param tab: Host list
      :type tab: list[alignak.objects.host.Host]
      :return: host_name list
      :rtype: list