docs: def import_directory(self, datadir):
          """ import a JSON directory into the database """
  
          def json_stream():
              # load all json, mapped by json_id
              for fname in glob.glob(os.path.join(datadir, self._type + '_*.json')):
                  with open(fname) as f:
                      yield json.load(f)
  
          return self.import_data(json_stream())