code: def monitor_instances(self, instance_ids):
          
          params = {}
          self.build_list_params(params, instance_ids, 'InstanceId')
          return self.get_list('MonitorInstances', params,
                               [('item', InstanceInfo)], verb='POST')
docs: Enable CloudWatch monitoring for the supplied instances.
  
          :type instance_id: list of strings
          :param instance_id: The instance ids
  
          :rtype: list
          :return: A list of :class:`boto.ec2.instanceinfo.InstanceInfo`