docs: def client_authentication(self, request, auth=None, **kwargs):
          """
          Do client authentication
  
          :param endpoint_context: A
              :py:class:`oidcendpoint.endpoint_context.SrvInfo` instance
          :param request: Parsed request, a self.request_cls class instance
          :param authn: Authorization info
          :return: client_id or raise and exception
          """
  
          return verify_client(self.endpoint_context, request, auth)