code: def update_submodules(repo_dir):
      """update submodules in a repo"""
      subprocess.check_call(
          "git submodule init", cwd=repo_dir, shell=True
      )
      subprocess.check_call(
          "git submodule update --recursive", cwd=repo_dir, shell=True
      )
  
imports: import os
  import subprocess
  import sys
  import warnings
  import shutil
label_desc: Use image node_id 4 for calling a global function with example usage: update_submodules(repo_dir) without return types