https://www.goinggo.net/2014/05/methods-interfaces-and-embedded-types.html

interface_call.go

package main

import "log"

type Admin struct {
	*User
	Level string
}

func (a *Admin) Notify() error {
	log.Printf("Admin: Sending Admin Email to %s<%s>\n",
		a.Name,
		a.Email)
	return nil
}

type User struct {
	Name  string
	Email string
}

func (u *User) Notify() error {
	log.Printf("User: Sending User Email to %s<%s>\n",
		u.Name,
		u.Email)
	return nil
}

type Notifier interface {
	Notify() error
}

func SendNotification(notify Notifier) error {
	return notify.Notify()
}

func main() {
	admin := &Admin {
		User: &User{"Bill", "bill@email.com"},
		Level: "super",
	}
	SendNotification(admin)
}