docs: def data_file(self):
          """Return the uncompressed raw CPIO data of the RPM archive."""
  
          if self._data_file is None:
              fileobj = _SubFile(self._fileobj, self.data_offset)
  
              if self.headers["archive_compression"] == b"xz":
                  if not getattr(sys.modules[__name__], 'lzma', False):
                      raise NoLZMAModuleError('lzma module not present')
                  self._data_file = lzma.LZMAFile(fileobj)
              else:
                  self._data_file = gzip.GzipFile(fileobj=fileobj)
  
          return self._data_file