code: func (m *TryMutex) Close() error {
  	//log.Debug("TryMutex: close")
  	if err := m.sess.Close(); err != nil {
  		log.Errorf("TryMutex: close err: %v", err)
  		return err
  	}
  	return nil
  }
docs: // Close closes and cleans up the underlying concurrency session.