code: def convert_conf_for_unreachable(params):
          
          if params is None:
              return
  
          for prop in ['flap_detection_options', 'notification_options',
                       'snapshot_criteria', 'stalking_options']:
              if prop in params:
                  params[prop] = [p.replace('u', 'x') for p in params[prop]]
  
          if 'initial_state' in params and \
                  (params['initial_state'] == 'u' or params['initial_state'] == ['u']):
              params['initial_state'] = 'x'
  
          if 'freshness_state' in params and \
                  (params['freshness_state'] == 'u' or params['freshness_state'] == ['u']):
              params['freshness_state'] = 'x'
docs: The 'u' state for UNREACHABLE has been rewritten in 'x' in:
          * flap_detection_options
          * notification_options
          * snapshot_criteria
  
          So convert value from config file to keep compatibility with Nagios
  
          :param params: parameters of the host before put in properties
          :type params: dict
          :return: None