code: def update_stations(cls, station_info_list):
      
      with cls.station_map_lock:
  
        # By default, assume old stations are unreachable.
        for host_port, station_info in six.iteritems(cls.station_map):
          cls.station_map[host_port] = station_info._replace(status='UNREACHABLE')
  
        for station_info in station_info_list:
          host_port = '%s:%s' % (station_info.host, station_info.port)
          cls.station_map[host_port] = station_info
docs: Called by the station discovery loop to update the station map.