Also, rename to stdmethods and add more tests.
Change-Id: I09b65899dc02a8062f3ec1d909c2eae45472e236
Reviewed-on: https://go-review.googlesource.com/c/140761
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>