code: def router_id(self, **kwargs):
          
          router_id = kwargs.pop('router_id')
          rbridge_id = kwargs.pop('rbridge_id', '1')
          callback = kwargs.pop('callback', self._callback)
          rid_args = dict(rbridge_id=rbridge_id, router_id=router_id)
          config = self._rbridge.rbridge_id_ip_rtm_config_router_id(**rid_args)
          return callback(config)
docs: Configures device's Router ID.
  
          Args:
              router_id (str): Router ID for the device.
              rbridge_id (str): The rbridge ID of the device on which BGP will be
                  configured in a VCS fabric.
              callback (function): A function executed upon completion of the
                  method.  The only parameter passed to `callback` will be the
                  ``ElementTree`` `config`.
  
          Returns:
              Return value of `callback`.
  
          Raises:
              KeyError: if `router_id` is not specified.
  
          Examples:
              >>> import pynos.device
              >>> conn = ('10.24.39.211', '22')
              >>> auth = ('admin', 'password')
              >>> with pynos.device.Device(conn=conn, auth=auth) as dev:
              ...     output = dev.system.router_id(router_id='10.24.39.211',
              ...     rbridge_id='225')
              ...     dev.system.router_id() # doctest: +IGNORE_EXCEPTION_DETAIL
              Traceback (most recent call last):
              KeyError