code: def _airflow_initdb(self):
      _ = subprocess.check_output(["airflow", "db", "init"])
  
imports: import codecs
  import locale
  import os
  import subprocess
  import sys
  import time
  import absl
  from click import testing
  import tensorflow
  from tfx.dsl.io import fileio
  from tfx.orchestration.airflow import test_utils
  from tfx.tools.cli import labels
  from tfx.tools.cli import pip_utils
  from tfx.tools.cli.cli_main import cli_group
  from tfx.tools.cli.e2e import test_utils
  from tfx.utils import io_utils
  from tfx.utils import retry
  from tfx.utils import test_case_utils
label_desc: Use image node_id 3 for calling the CliAirflowEndToEndTest obj's underlying member method code with example usage: obj._airflow_initdb() without return types