def get_instance_attribute(self, instance_id, attribute):
        params = {'InstanceId' : instance_id}
        if attribute:
            params['Attribute'] = attribute
        return self.get_object('DescribeInstanceAttribute', params,
                               InstanceAttribute, verb='POST')
Deletes unused indexes.
dataset/ETHPy150Open darcyliu/storyboard/boto/ec2/connection.py/EC2Connection.get_instance_attribute--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/tools/appcfg.py/AppCfgApp.VacuumIndexes