authToken := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9" authorizer := AuthorizerImpl{} authTag := authorizer.GetAuthTag(authToken)
dataBytes, err := json.Marshal(userData) if err != nil { log.Printf("error marshalling userData: %v", err) return "", ErrInvalidRequest } authToken, err := generateToken(dataBytes) if err != nil { log.Printf("error generating token: %v", err) return "", ErrUnauthorized } authorizer := AuthorizerImpl{} authTag := authorizer.GetAuthTag(authToken)In this example, we first marshal some user data to a JSON object and generate an authentication token using a custom `generateToken` function. We then create an instance of `AuthorizerImpl` and pass in the generated authentication token to the `GetAuthTag` method of the authorizer. The returned `authTag` is a string representing the authorization tag for the given token. Both examples use the `GetAuthTag` method of the `Authorizer` interface of the `github.com/juju/juju/apiserver/common` library to obtain the authorization tag for an authentication token.