code: def test_doc_files_are_notebooks(doc_file):
      nb = read(doc_file)
  
      # count how many cell types
      counts = {"markdown": 0, "raw": 0, "code": 0}
      for cell in nb.cells:
          counts[cell.cell_type] += 1
  
      assert counts["raw"] <= 1
  
imports: from pathlib import Path
  import pytest
  from jupytext import read
label_desc: Use image node_id 2 for calling a global function with example usage: test_doc_files_are_notebooks(doc_file) without return types