code: def test_sample_notebook():
      here = os.path.dirname(__file__)
      with open(
          os.path.join(
              here, os.pardir, os.pardir, "tests", "test4.ipynb"
          ),
          encoding="utf-8",
      ) as f:
          nb = reads(f.read())
      validate4(nb)
  
file_path: nbformat/tests/v4/test_validate.py
imports: from __future__ import annotations
  import os
  import pytest
  from nbformat.v4.nbbase import nbformat, new_code_cell, new_markdown_cell, new_raw_cell
  from nbformat.v4.nbjson import reads
  from nbformat.validator import ValidationError, validate
label_desc: Use image node_id 6 for calling a global function with example usage: test_sample_notebook() without return types