code: func (n *node) Rollback() error {
  	if n.tx == nil {
  		return ErrNotInTransaction
  	}
  
  	err := n.tx.Rollback()
  	if err == bolt.ErrTxClosed {
  		return ErrNotInTransaction
  	}
  
  	return err
  }
docs: // Rollback closes the transaction and ignores all previous updates.