def METHOD_NAME(tmp_path, python_notebook):
    cm = TextFileContentsManager()
    cm.root_dir = str(tmp_path)
    nb = python_notebook
    nb.cells.append(new_code_cell(source="1+1", outputs=[new_output("execute_result")]))
    nb.metadata["jupytext"] = {"formats": "ipynb,md:myst"}
    cm.notary.unsign(nb)
    cm.save(model=dict(type="notebook", content=nb), path="test.ipynb")
    nb = cm.get("test.md")["content"]
    assert not cm.notary.check_cells(nb)
    assert not cm.notary.check_signature(nb)