docs: def close(self):
          """Close any open connections to Redis.
  
          :raises: :exc:`tredis.exceptions.ConnectionError`
  
          """
          if not self._connected.is_set():
              raise exceptions.ConnectionError('not connected')
          self._closing = True
          if self._clustering:
              for host in self._cluster.keys():
                  self._cluster[host].close()
          elif self._connection:
              self._connection.close()