'Convert the stored values into a WWW-Authenticate header.'

def to_header(self):

    d = dict(self)
    auth_type = (d.pop('__auth_type__', None) or 'basic')
    return ('%s    %s' % (auth_type.title(), ',    '.join([('%s=%s' % (key, quote_header_value(value, allow_token=(key not in self._require_quoting)))) for (key, value) in iteritems(d)])))
