code: func (e OptimisticLockError) Error() string {
  	if e.RowExists {
  		return fmt.Sprintf("gorp: OptimisticLockError table=%s keys=%v out of date version=%d", e.TableName, e.Keys, e.LocalVersion)
  	}
  
  	return fmt.Sprintf("gorp: OptimisticLockError no row found for table=%s keys=%v", e.TableName, e.Keys)
  }
docs: // Error returns a description of the cause of the lock error