code: def main(args):
      client = boto3.client(
          "cloudformation", region_name=args.aws_region
      )
  
      agent_iam_policy = create_agent_iam_policy(args, client=client)
  
      promises = []
  
      for stack_id in AMI_ID:
          stack_id_full = get_full_stack_id(stack_id)
          print(f"Creating elastic CI stack {stack_id_full}...")
  
          params = format_params(
              args, stack_id=stack_id, agent_iam_policy=agent_iam_policy
          )
  
          promise = create_or_update_stack(
              args,
              client=client,
              stack_name=stack_id_full,
              template_url=TEMPLATE_URL,
              params=params,
          )
          promises.append(promise)
          print(
              f"CI stack {stack_id_full} is in progress in the background"
          )
  
      for promise in promises:
          wait(promise, client=client)
  
file_path: xgboost/tests/buildkite/infrastructure/aws-stack-creator/create_stack.py
imports: import argparse
  import copy
  import os
  import re
  import sys
  import boto3
  import botocore
  from metadata import AMI_ID, COMMON_STACK_PARAMS, STACK_PARAMS
  from common_blocks.utils import create_or_update_stack, wait
label_desc: Use image node_id 6 for calling a global function with example usage: main(args) without return types