code: def test_shell(self):
      proc = self.loop.run_until_complete(
          asyncio.create_subprocess_shell("exit 7")
      )
      exitcode = self.loop.run_until_complete(proc.wait())
      self.assertEqual(exitcode, 7)
  
imports: import os
  import signal
  import sys
  import textwrap
  import unittest
  import warnings
  from unittest import mock
  import asyncio
  from asyncio import base_subprocess
  from asyncio import subprocess
  from test.test_asyncio import utils
  from test import support
  from test.support import os_helper
label_desc: Use image node_id 4 for calling the SubprocessMixin obj's underlying member method code with example usage: obj.test_shell() without return types