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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def monitor_instances(self, instance_ids):
 """ 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` """

        params = {}
        self.build_list_params(params, instance_ids, 'InstanceId')
        return self.get_list('MonitorInstances', params,
                             [('item', InstanceInfo)], verb='POST')