code: def default_formats(self, path):
          
          formats = long_form_multiple_formats(self.default_jupytext_formats)
          for fmt in formats:
              try:
                  base_path(path, fmt)
                  return self.default_jupytext_formats
              except InconsistentPath:
                  continue
  
          return None
docs: Return the default formats, if they apply to the current path #157