import ( "github.com/cockroachdb/cockroach/pkg/roachpb" "github.com/cockroachdb/cockroach/pkg/storage/engine" ) // create a new CockroachDB engine eng, err := engine.NewInMem(roachpb.Attributes{}, 1<<20) if err != nil { panic(err) } // create a new transaction txn := roachpb.MakeTransaction("test", []byte{}, roachpb.ReasonUserTransaction, 0, enginepb.SERIALIZABLE, enginepb.SERIALIZABLE, nil) // set the value of key "hello" to "world" err = engine.MVCCPut(context.Background(), eng, nil, []byte("hello"), txn.ReadTimestamp, roachpb.MakeValueFromString("world"), txn) if err != nil { panic(err) } // get the value of key "hello" res, _, err := engine.MVCCGet(context.Background(), eng, []byte("hello"), txn.ReadTimestamp, engine.MVCCGetOptions{}) if err != nil { panic(err) } // print the value fmt.Println(res.String())This code creates a new CockroachDB engine, starts a transaction, sets the value of key "hello" to "world" using the MVCCPut method, gets the value using the MVCCGet method, and prints the value. The roachpb.Value struct is used to represent the value of the key. Overall, the cockroach.pkg.roachpb package library provides structs and methods for handling CockroachDB keys and values in Go.