Emacs function to kill added/removed lines of diff output, removing the diff markers

kill-diff.el

(defun dm/kill-diff (arg)
  "Kill added/removed lines of diff output, removing the diff markers.
Without a prefix argument or a positive argument, kill the added
lines.  With a negative argument, kill the removed lines."
  (interactive "P")
  (kill-new
     (thread-last (buffer-substring-no-properties
                   (region-beginning)
                   (region-end))
       (replace-regexp-in-string
        (format "^\\%c.*\n?" (if (< (prefix-numeric-value arg) 0) ?+ ?-))
        "")
       (replace-regexp-in-string "^[ \\+\\-]" ""))))