docs: def __remove_obsolete_metadata(self):
          """
          Removes obsolete entries from the metadata of all stored routines.
          """
          clean = {}
          for key, _ in self._source_file_names.items():
              if key in self._pystratum_metadata:
                  clean[key] = self._pystratum_metadata[key]
  
          self._pystratum_metadata = clean