code: def _auth_header(self, type, **options):
          
          return '%s %s' % (type.title(), ', '.join((
              '%s=%s' % (key, quote_header_value(
                  value, allow_token=key not in _require_quoting))
              for key, value in options.items()
          )))
docs: Convert the stored values into a WWW-Authenticate header.