code: def test_meaningfull_error_open_myst_missing(tmpdir):
      md_file = tmpdir.join("notebook.md")
      md_file.write(
          """---
  jupytext:
    text_representation:
      extension: '.md'
      format_name: myst
  kernelspec:
    display_name: Python 3
    language: python
    name: python3
  ---
  
  1 + 1
  """
      )
  
      with pytest.raises(ImportError, match=PLEASE_INSTALL_MYST):
          jupytext_cli([str(md_file), "--to", "ipynb"])
  
      cm = jupytext.TextFileContentsManager()
      cm.root_dir = str(tmpdir)
  
      with pytest.raises(HTTPError, match=PLEASE_INSTALL_MYST):
          cm.get("notebook.md")
  
imports: import json
  import unittest.mock
  from textwrap import dedent
  import pytest
  from nbformat.v4.nbbase import new_notebook
  from tornado.web import HTTPError
  import jupytext
  from jupytext.cli import jupytext
  from jupytext.compare import compare
  from jupytext.formats import JupytextFormatError, get_format_implementation, guess_format
  from jupytext.myst import CODE_DIRECTIVE, MystMetadataParsingError, matches_mystnb, myst_extensions, myst_to_notebook
label_desc: Use image node_id 9 for calling a global function with example usage: test_meaningfull_error_open_myst_missing(tmpdir) without return types