Available from Manning Publications https://www.manning.com/books/get-programming-with-go.
Try out these examples in The Go Playground: https://play.golang.org
If you downloaded this code from the Manning website, you can browse the latest version online at: https://github.com/nathany/get-programming-with-go.
Feel free to open an issue or ask questions on the Manning LiveBook: https://forums.manning.com/forums/get-programming-with-go.