Shortening words in a selected region

[uzibalqa via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

Have the following function to shorten specific words, inserting `k' for words with initial `cog', `col', `com', `con',

`cor', `coun', `cum'. The word "corrupt" then becomes "krupt". One simply puts the cursor point on a word and
execute the function using "M-x shorten-word".

I would like to have an equivalent function that works on words in a selected region this time round.

(defun shorten-word ()
"Shortens certain words by introducing the letter 'k'."

(interactive)
(let* ( (bounds (bounds-of-thing-at-point 'word))
(word (buffer-substring (car bounds) (cdr bounds)))
(point (point)) )

(goto-char (car bounds))
(delete-char (length word)) (insert (replace-regexp-in-string "\\<\\(co[glmnr]\\|coun\\|cum\\)" "k" word))

(goto-char point)))