code: def request_challenges(self, identifier):
          
          action = LOG_ACME_CREATE_AUTHORIZATION(identifier=identifier)
          with action.context():
              message = messages.NewAuthorization(identifier=identifier)
              return (
                  DeferredContext(
                      self._client.post(self.directory[message], message))
                  .addCallback(self._expect_response, http.CREATED)
                  .addCallback(self._parse_authorization)
                  .addCallback(self._check_authorization, identifier)
                  .addCallback(
                      tap(lambda a: action.add_success_fields(authorization=a)))
                  .addActionFinish())
docs: Create a new authorization.
  
          :param ~acme.messages.Identifier identifier: The identifier to
              authorize.
  
          :return: The new authorization resource.
          :rtype: Deferred[`~acme.messages.AuthorizationResource`]