Q: What does it mean that Go doesn't support Generics? -- A: This snippet.

no_generics.go

package main

import (
	"fmt"
)

type Whatever interface {
	foo()
}

// This is not allowed.
//func (w Whatever) foo() {
//	fmt.Println("w.foo")
//}

type SomethingElse struct {
	s string
}

func (b SomethingElse) foo() {
	fmt.Println("b.foo")
}

func DoSomethingWithWhatever(w Whatever) {
	w.foo()
}

func main() {
	s := SomethingElse{}
	DoSomethingWithWhatever(s)
}