code: def test_rearrange_jupytext_metadata_add_dot_in_suffix():
      metadata = {
          "jupytext": {
              "text_representation": {"jupytext_version": "0.8.6"},
              "formats": "ipynb,pct.py,lgt.py",
          }
      }
      rearrange_jupytext_metadata(metadata)
      compare(
          metadata,
          {
              "jupytext": {
                  "text_representation": {"jupytext_version": "0.8.6"},
                  "formats": "ipynb,.pct.py,.lgt.py",
              }
          },
      )
  
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 21 for calling a global function with example usage: test_rearrange_jupytext_metadata_add_dot_in_suffix() without return types