code: func (r *RollbackTx) MaybeRollback(c context.Context) error {
  	if !r.committed {
  		if err := r.Tx.Rollback(); err != nil {
  			errors.Log(c, errors.Annotate(err, "failed to roll back transaction").Err())
  			return err
  		}
  	}
  	return nil
  }
docs: // MaybeRollback rolls back the transaction if (*RollbackTx).Commit() hasn't been called.
  // Logs the error if the rollback itself fails.