def METHOD_NAME(md_dir, aishell1_dir):
    # If md_dir already exists then check the already generated files
    already_generated_csv = os.listdir(md_dir)
    # Save the already generated files names
    already_generated_csv = [f.split(".")[0] for f in already_generated_csv]
    # Possible directories in the original aishell1
    original_aishell1_dirs = ["dev", "test", "train"]
    # Actual directories extracted in your aishell1 version
    actual_aishell1_dirs = set(next(os.walk(aishell1_dir))[1]) & set(
        original_aishell1_dirs
    )
    # Actual directories that haven't already been processed
    not_already_processed_directories = list(
        set(actual_aishell1_dirs) - set(already_generated_csv)
    )
    return not_already_processed_directories