`Errorf` should be able to wrap errors

I expected Errorf to mimic fmt.Errorf's behavior of wrapping errors. Alas, that was not the case. I was wondering if this is intentional or not. If it's intentional, then is there a way of formatting wrapping errors as '(wrapped error): outer error'?

Here's a playground link explaining what I'm talking about. https://play.golang.org/p/yDjjs_8GsSY