code: def test_test_round_trip_conversion():
      notebook = new_notebook(
          cells=[
              new_code_cell(
                  "1+1",
                  outputs=[
                      {
                          "data": {"text/plain": ["2"]},
                          "execution_count": 1,
                          "metadata": {},
                          "output_type": "execute_result",
                      }
                  ],
              )
          ],
          metadata={"main_language": "python"},
      )
  
      round_trip_conversion(notebook, {"extension": ".py"}, update=True)
  
imports: import pytest
  from nbformat.v4.nbbase import new_code_cell, new_markdown_cell, new_notebook, new_raw_cell
  from jupytext.compare import NotebookDifference, compare, compare_cells, compare_notebooks
  from jupytext.compare import test_round_trip_conversion
label_desc: Use image node_id 16 for calling a global function with example usage: test_test_round_trip_conversion() without return types