Cancel the specified Spot Instance Requests.

        :type request_ids: list
        :param request_ids: A list of strings of the Request IDs to terminate

        :rtype: list
        :return: A list of the instances terminated

def cancel_spot_instance_requests(self, request_ids):
        """
        Cancel the specified Spot Instance Requests.

        :type request_ids: list
        :param request_ids: A list of strings of the Request IDs to terminate

        :rtype: list
        :return: A list of the instances terminated
        """
        params = {}
        if request_ids:
            self.build_list_params(params, request_ids, 'SpotInstanceRequestId')
        return self.get_list('CancelSpotInstanceRequests', params,
                             [('item', Instance)], verb='POST')