NOTE About printer library package: printer.go file must reside under /printer directory. This is because the name of that library package is printer. About goversion library package: goversion.go file must reside under /goversion directory. This is because the name of that library package is goversion. Only Func names starting with upper case letter will get exported. To Execute NOTE: CMD+e+e (Run Code extension in VS Code) won't work directly on main.go. We must have to execute go run main.go command. printer library package: Go to: cd src/github.com/aditya43/golang/005-Exporting/printer/cmd/ Run command: go run main.go goversion library package: Go to: cd src/github.com/aditya43/golang/005-Exporting/goversion/cmd/ Run command: go run main.go