code: def test_read_write_script(
      pynb="""#!/usr/bin/env python
  # coding=utf-8
  print('Hello world')
  """,
  ):
      nb = jupytext.reads(pynb, "py")
      pynb2 = jupytext.writes(nb, "py")
      compare(pynb2, pynb)
  
imports: import pytest
  from nbformat.v4.nbbase import new_code_cell, new_markdown_cell, new_notebook, new_raw_cell
  import jupytext
  from jupytext.compare import compare, compare_notebooks
label_desc: Use image node_id 22 for calling a global function with example usage: test_read_write_script(pynb) without return types