code: def open(self, host, port=23):
          
          self._telnet_client.open(host, port)
          config_str = self._telnet_client.cmd("MN?")
          if config_str.startswith("MN="):
              config_str = config_str[len("MN="):]
          self.properties = dict(
              zip(['model', 'max_freq', 'max_atten'], config_str.split("-", 2)))
          self.max_atten = float(self.properties['max_atten'])
docs: Opens a telnet connection to the desired AttenuatorDevice and
          queries basic information.
  
          Args:
              host: A valid hostname (IP address or DNS-resolvable name) to an
                  MC-DAT attenuator instrument.
              port: An optional port number (defaults to telnet default 23)