Powerful Command-Line Applications in Go: missing go get commands (page 85)

Paragraph 3.
Before you can use these external packages in your program, you need to install them in your local machine. In Go, you install external packages by using the go get tool. To install these two packages, run the following commands:

NO COMMANDS PRESENT HERE

Since you’re using Go modules, you do not need to download these packages in advance. You’ll add them to the import list in main.go and Go will download them automatically when required. You do need an Internet connection for this download to work though.