docs: def unquote(s):
      """unquote('abc%20def') -> 'abc def'."""
      res = s.split('%')
      # fastpath
      if len(res) == 1:
          return s
      s = res[0]
      for item in res[1:]:
          try:
              s += _hextochr[item[:2]] + item[2:]
          except KeyError:
              s += '%' + item
          except UnicodeDecodeError:
              s += chr(int(item[:2], 16)) + item[2:]
      return s