docs: def clone_source_dir(source_dir, dest_dir):
      """Copies the source Protobuf files into a build directory.
  
      Args:
          source_dir (str): source directory of the Protobuf files
          dest_dir (str): destination directory of the Protobuf files
      """
      if os.path.isdir(dest_dir):
          print('removing', dest_dir)
          shutil.rmtree(dest_dir)
      shutil.copytree(source_dir, dest_dir)