code: def test_read_mostly_R_markdown_file(
      markdown="""```R
  ls()
  ```
  
  ```R
  cat(stringi::stri_rand_lipsum(3), sep='\n\n')
  ```
  """,
  ):
      nb = jupytext.reads(markdown, "md")
      assert nb.metadata["jupytext"]["main_language"] == "R"
      compare_cells(
          nb.cells,
          [
              new_code_cell("ls()"),
              new_code_cell(
                  "cat(stringi::stri_rand_lipsum(3), sep='\n\n')"
              ),
          ],
          compare_ids=False,
      )
  
      markdown2 = jupytext.writes(nb, "md")
      compare(markdown2, markdown)
  
imports: from nbformat.v4.nbbase import new_code_cell, new_markdown_cell, new_notebook, new_raw_cell
  import jupytext
  from jupytext.combine import combine_inputs_with_outputs
  from jupytext.compare import compare, compare_cells, compare_notebooks
label_desc: Use image node_id 3 for calling a global function with example usage: test_read_mostly_R_markdown_file(markdown) without return types