This change adds several examples, with emphasis on special or edge
cases such as a directory parameter consisting of an empty string.

Change-Id: Ib4ac3d0f6d503493eeed0c4fda7c12acf782e9e2
Reviewed-on: https://go-review.googlesource.com/43010Reviewed-by: Steve Francia <spf@golang.org>
Run-TryBot: Jaana Burcu Dogan <jbd@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>