code: def test_update_jupytext_formats_metadata():
      nb = new_notebook(metadata={"jupytext": {"formats": "py"}})
      update_jupytext_formats_metadata(nb.metadata, "py:light")
      assert nb.metadata["jupytext"]["formats"] == "py:light"
  
      nb = new_notebook(metadata={"jupytext": {"formats": "ipynb,py"}})
      update_jupytext_formats_metadata(nb.metadata, "py:light")
      assert nb.metadata["jupytext"]["formats"] == "ipynb,py:light"
  
imports: import pytest
  from nbformat.v4.nbbase import new_notebook
  import jupytext
  from jupytext.compare import compare
  from jupytext.formats import JupytextFormatError, divine_format, get_format_implementation, guess_format, long_form_multiple_formats, read_format_from_metadata, rearrange_jupytext_metadata, short_form_multiple_formats, update_jupytext_formats_metadata, validate_one_format
label_desc: Use image node_id 16 for calling a global function with example usage: test_update_jupytext_formats_metadata() without return types