package main

import "fmt"

type A struct {
id int
}

type Builder interface {
add() A
remove() A
}

func (a A) add(el int) A{
a.id = el
return a
}

func (a A) remove() A{
a.id = 0
return a
}

func main() {
n := A{1}

fmt.Println(n.add(2).remove())
}