example.go

type Node interface {
        Prepare()
        Run()
}

func doSomeWork(n Node) {
        // ...
        n.Prepare()
        // ...
        n.Run()
        // ...
}

type Command struct {}

func (Command) Prepare() {
        // ...
}

func (Command) Run() {
        // ...
}

type Spawner struct {}

func (Spawner) Prepare() {
        // ...
}

func (Spawner) Run() {
        // ...
}