This is the second day of my participation in Gwen challenge
Multi, mark the start of a transaction block, return ok exec, execute all commands in the transaction block, return null discard, cancel the transaction, discard all commands in the transaction block, return OK watch, Monitor whether the key is changed by other instructions before the transaction execution. If it is changed, the instructions in the transaction are cancelled and ok unwatch is returned. Cancel the watch command’s monitoring of the key and OK is returned