F url_decode(s)
   V r = ‘’
   V i = 0
   L i < s.len
      I s[i] == ‘%’
         [Byte] b
         L i < s.len & s[i] == ‘%’
            i++
            b.append(Int(s[i.+2], radix' 16))
            i += 2
         r ‘’= b.decode(‘utf-8’)
      E
         r ‘’= s[i]
         i++
   R r

print(url_decode(‘http%3A%2F%2Ffoo%20bar%2F’))
print(url_decode(‘https://ru.wikipedia.org/wiki/%D0%A2%D1%80%D0%B0%D0%BD%D1%81%D0%BF%D0%B0%D0%B9%D0%BB%D0%B5%D1%80’))