code: def agree_to_tos(self, regr):
          
          return self.update_registration(
              regr.update(
                  body=regr.body.update(
                      agreement=regr.terms_of_service)))
docs: Accept the terms-of-service for a registration.
  
          :param ~acme.messages.RegistrationResource regr: The registration to
              update.
  
          :return: The updated registration resource.
          :rtype: Deferred[`~acme.messages.RegistrationResource`]