code: def code(item):
      
      _res = []
      i = 0
      for attr in ATTR:
          val = getattr(item, attr)
          if val:
              _res.append("%d=%s" % (i, quote(val)))
          i += 1
      return ",".join(_res)
docs: Turn a NameID class instance into a quoted string of comma separated
      attribute,value pairs. The attribute names are replaced with digits.
      Depends on knowledge on the specific order of the attributes for the
      class that is used.
  
      :param item: The class instance
      :return: A quoted string