code: def test_black_invariant():
      text_org = """long_string = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" \\
                "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
  """
      text_black = """long_string = (
      "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
      "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
  )
  """
      assert black_invariant(text_org) == black_invariant(text_black)
  
imports: import os
  from copy import deepcopy
  from shutil import copyfile
  import pytest
  from nbformat.v4.nbbase import new_code_cell, new_notebook
  from jupytext import read, write
  from jupytext.cli import jupytext, pipe_notebook, system
  from jupytext.combine import black_invariant
  from jupytext.compare import compare, compare_cells, compare_notebooks
  from jupytext.header import _DEFAULT_NOTEBOOK_METADATA
label_desc: Use image node_id 2 for calling a global function with example usage: test_black_invariant() without return types