sample of interface for golang

interface.go

package main

import (
        "fmt"
)

type Animal interface {
        Cow() string
}

type Horse struct{}

func (_ Horse) Cow() string {
        return "xyz"
}

type Turtle struct{}

func (_ Turtle) Cow() string {
        return "Doo"
}

func PrintCow(a Animal) {
        fmt.Println(a.Cow())
}

func main() {
        animal := new(Turtle)
        PrintCow(animal)
}