code: def add_monitor(self, actor, monitor_name, **params):
          '''Add a new ``monitor``.
  
          :param monitor_class: a :class:`.Monitor` class.
          :param monitor_name: a unique name for the monitor.
          :param kwargs: dictionary of key-valued parameters for the monitor.
          :return: the :class:`.Monitor` added.
          '''
          if monitor_name in self.registered:
              raise KeyError('Monitor "%s" already available' % monitor_name)
          params.update(actor.actorparams())
          params['name'] = monitor_name
          params['kind'] = 'monitor'
          return actor.spawn(**paramsf add_monitor(self, actor, monitor_name, **params):
          '''Add a new ``monitor``.
  
          :param monitor_class: a :class:`.Monitor` class.
          :param monitor_name: a unique name for the monitor.
          :param kwargs: dictionary of key-valued parameters for the monitor.
          :return: the :class:`.Monitor` added.
          '''
          if monitor_name in self.registered:
              raise KeyError('Monitor "%s" already available' % monitor_name)
          params.update(actor.actorparams())
          params['name'] = monitor_name
          params['kind'] = 'monitor'
          return actor.spawn(**params)
docs: Add a new ``monitor``.
  
          :param monitor_class: a :class:`.Monitor` class.
          :param monitor_name: a unique name for the monitor.
          :param kwargs: dictionary of key-valued parameters for the monitor.
          :return: the :class:`.Monitor` added.