Emacs Lisp: Should Directory Name Ends in a Slash?
In emacs lisp, dir path should end in a slash.
when your command query user for dir path, user may not add the ending slash. Your program can add it, like this:
(setq inputDir (file-name-as-directory inputDir) ) ; normalize dir path
file-name-as-directory is better than writing code to check and append slash yourself.