The method signature does not explain much about how to use the
function, and which arguments to invoke it with, so an example would
be helpful.

Change-Id: I95747567b2cafe70da1e04939c39f6b507f12684
Reviewed-on: https://go-review.googlesource.com/130317Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>