code: func (s *store) GetTxPvtRWSetByTxid(txid string, filter ledger.PvtNsCollFilter) (RWSetScanner, error) {
  
  	logger.Debugf("Getting private data from transient store for transaction %s", txid)
  
  	// Construct startKey and endKey to do an range query
  	startKey := createTxidRangeStartKey(txid)
  	endKey := createTxidRangeEndKey(txid)
  
  	iter := s.db.GetIterator(startKey, endKey)
  	return &RwsetScanner{txid, iter, filter}, nil
  }
docs: // GetTxPvtRWSetByTxid returns an iterator due to the fact that the txid may have multiple private
  // write sets persisted from different endorsers.