code: def encode_rfc2231(s, charset=None, language=None):
      
      s = url_quote(s, safe='', encoding=charset or 'ascii')
      if charset is None and language is None:
          return s
      if language is None:
          language = ''
      return "%s'%s'%s" % (charset, language, s)
docs: Encode string according to RFC 2231.
  
      If neither charset nor language is given, then s is returned as-is.  If
      charset is given but not language, the string is encoded using the empty
      string for language.