Example of interface wrapping erasure

abstract_example.go

package main

// Given an interface
type I interface {
	Func()
}

// And another interface
type I2 interface {
	Another()
}

// And a struct that implements both
type S struct {
}

var _ I = &S{}
var _ I2 = &S{}

func (s *S) Func()    {}
func (s *S) Another() {}

// If you want to augment an interface (but didn't know about I2)
type IChain struct {
	I
}

func Augment(i I) I {
	return &IChain{i}
}

func main() {
	var s I
	s = &S{}
	_ = s.(I2)
	s = Augment(s)
	// You lose your implementation of the base interface
	_ = s.(I2)
}

*lose