code: func (g *Graveyard) RestoreTxn(tx *memdb.Txn, stone *Tombstone) error {
  	if err := tx.Insert("tombstones", stone); err != nil {
  		return fmt.Errorf("failed inserting tombstone: %s", err)
  	}
  
  	if err := indexUpdateMaxTxn(tx, stone.Index, "tombstones"); err != nil {
  		return fmt.Errorf("failed updating index: %s", err)
  	}
  	return nil
  }
docs: // RestoreTxn is used when restoring from a snapshot. For general inserts, use
  // InsertTxn.