binding a summary key to *two* commands

[Hikaru Ichijyo]

Anyone have any idea how I could make *two* summary buffer commands emit
from one keystroke?  I've tried the snippet below, but it's giving me
errors about the wrong number of arguments.  Basically, I'm trying to
make "D" expire and read next unread, while "d" just expires and moves
forward without reading.  The only part not working here is the "D".


(defun delete-then-read-next ()
  (interactive)
  (gnus-summary-mark-as-expirable)
  (gnus-summary-next-unread-article)
)
(add-to-list 'mm-attachment-override-types "image/.*")
(add-hook 'gnus-select-group-hook 'gnus-group-set-timestamp)
(add-hook 'gnus-summary-mode-hook (lambda ()
    (local-set-key "D" 'delete-then-read-next)
    (local-set-key "d" 'gnus-summary-put-mark-as-expirable-next)
    (local-set-key "u" 'gnus-summary-clear-mark-forward)
    (local-set-key "x" 'gnus-summary-expire-articles)
    (local-set-key "s" 'gnus-summary-move-article)))

-- 
He that would make his own liberty secure must guard even his enemy from
oppression; for if he violates this duty, he establishes a precedent
that will reach to himself.
                                        --Thomas Paine