code: def insert_jupytext_info_and_filter_metadata(metadata, ext, text_format):
      
      if insert_or_test_version_number():
          metadata.setdefault('jupytext', {})['text_representation'] = {
              'extension': ext,
              'format_name': text_format.format_name,
              'format_version': text_format.current_version_number,
              'jupytext_version': __version__}
  
      if 'jupytext' in metadata and not metadata['jupytext']:
          del metadata['jupytext']
  
      notebook_metadata_filter = metadata.get('jupytext', {}).get('notebook_metadata_filter')
      return filter_metadata(metadata, notebook_metadata_filter, _DEFAULT_NOTEBOOK_METADATA)
docs: Update the notebook metadata to include Jupytext information, and filter
      the notebook metadata according to the default or user filter