code: func (r *raftLog) Set(k, v []byte) error {
  	r.Lock()
  	tx, err := r.conn.Begin(true)
  	if err != nil {
  		r.Unlock()
  		return err
  	}
  	bucket := tx.Bucket(confBucket)
  	err = bucket.Put(k, v)
  	if err != nil {
  		tx.Rollback()
  	} else {
  		err = tx.Commit()
  	}
  	r.Unlock()
  	return err
  }
docs: // Set implements the Stable interface