code: def test_simple(client):
      batch = create_batch(client)
      head = batch.create_job(
          DOCKER_ROOT_IMAGE, command=["echo", "head"]
      )
      batch.create_job(
          DOCKER_ROOT_IMAGE, command=["echo", "tail"], parents=[head]
      )
      batch.submit()
      batch.wait()
      status = legacy_batch_status(batch)
      assert batch_status_job_counter(status, "Success") == 2, str(
          (status, batch.debug_info())
      )
      assert all(j["exit_code"] == 0 for j in status["jobs"]), str(
          batch.debug_info()
      )
  
imports: import asyncio
  import os
  import re
  import secrets
  import pytest
  from aiohttp import web
  from hailtop.batch_client import aioclient
  from hailtop.batch_client.client import BatchClient, Job
  from .utils import DOCKER_ROOT_IMAGE, batch_status_job_counter, create_batch, legacy_batch_status
label_desc: Use image node_id 2 for calling a global function with example usage: test_simple(client) without return types