docs: def _many_to_many(self):
          """Perform many-to-many files conversion.
          :return: None
          :rtype: :py:obj:`None`
          """
          if not self.file_generator.to_path_compression:
              self._to_dir(self.file_generator)
          elif self.file_generator.to_path_compression == "zip":
              self._to_zipfile(self.file_generator)
          elif self.file_generator.to_path_compression in ("tar", "tar.gz", "tar.bz2"):
              self._to_tarfile(self.file_generator)
          elif self.file_generator.to_path_compression in ("gz", "bz2"):
              raise TypeError('Many-to-one conversion, cannot convert "{}" into "{}"'.format(self.file_generator.from_path,
                                                                                             self.file_generator.to_path))
          else:
              raise TypeError('Unknown output file format: "{}"'.format(self.file_generator.to_path))