Ensures that it compiles and makes it more discoverable in godoc. Change-Id: I50a3deb23110017d0eb16b1da0ac729a96ff2602 Reviewed-on: https://go-review.googlesource.com/40952 Run-TryBot: Alex Vaghin <ddos@google.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>