code: def ls(self, glob_str):
          
          path = os.path.join(self.uri, glob_str)
          return [os.path.split(s)[1] for s in glob.glob(path)]
docs: Return just the filenames that match `glob_str` inside the store directory.
  
          :param str glob_str: A glob string, i.e. 'state_*'
          :return: list of matched keys