Emacs: Adding Tab and Shift-Tab to Browse Kill Ring

The Browse Kill Ring Extension is great:

christopher@theoden ~$ guix show emacs-browse-kill-ring 
name: emacs-browse-kill-ring
version: 2.0.0-0.1ef72cc
outputs: out
systems: x86_64-linux i686-linux
dependencies: 
location: gnu/packages/emacs-xyz.scm:22330:4
homepage: https://github.com/browse-kill-ring/browse-kill-ring
license: GPL 2+
synopsis: Interactively insert items from kill-ring  
description: Did you ever feel that `C-y M-y M-y M-y ...' is not a great way of trying to find that piece of text you know you killed a while back? Then
+ `browse-kill-ring.el' is for you.

The obvious thing that is missing, however, is an easy way to jump to the next kill ring entry once you are in the *Kill Ring* buffer. These .emacs additions allow you to use TAB and SHIFT-TAB for that purpose:

(define-key browse-kill-ring-mode-map
  (kbd "<tab>") #'browse-kill-ring-forward)

(define-key browse-kill-ring-mode-map
  (kbd "<backtab>") #'browse-kill-ring-previous)