This task (the reverse of [[URL encoding]] and distinct from [[URL parser]]) is to provide a function
or mechanism to convert an URL-encoded string into its original unencoded form.

'''Test cases'''

*The encoded string "<code><nowiki>http%3A%2F%2Ffoo%20bar%2F</nowiki></code>" should be reverted to the unencoded form "<code><nowiki>http://foo bar/</nowiki></code>".

*The encoded string "<code><nowiki>google.com/search?q=%60Abdu%27l-Bah%C3%A1</nowiki></code>" should revert to the unencoded form "<code><nowiki>google.com/search?q=`Abdu'l-Bahá</nowiki></code>".