docs: def refresh(self, key, ttl, prev_value=None, prev_index=None,
                  timeout=None):
          """Sets only a TTL of a key.  The waiters doesn't receive notification
          by this operation.
          """
          return self.adapter.set(key, ttl=ttl, refresh=True,
                                  prev_value=prev_value, prev_index=prev_index,
                                  timeout=timeout)