Example usage of functionality implemented in CL 66710.

Change-Id: I87d6e4d2fb7a60e4ba1e6ef02715480eb7e8f8bd
Reviewed-on: https://go-review.googlesource.com/76011
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>