code: def flush_to_index(self):
          
          assert self._smref is not None
          # should always have a file here
          assert not isinstance(self._file_or_files, BytesIO)
  
          sm = self._smref()
          if sm is not None:
              index = self._index
              if index is None:
                  index = sm.repo.index
              # END handle index
              index.add([sm.k_modules_file], write=self._auto_write)
              sm._clear_cache()
docs: Flush changes in our configuration file to the index