Assistant: 
User: 
    Please analyze the following code file and determine whether it belongs to any of the provided modules based on the listed module descriptions.
    Note that the provided list of modules may not be exhaustive, and some files may not belong to any of the modules. 
    If the code belongs to a module, Only output the module name, without any explanation or additional information; otherwise, return 'None' if it does not belong to any module.

    Modules : {
        "UI": "Handles the front-end user interface, consisting of HTML, CSS, and JavaScript files generated by the Angular framework. It processes user requests and interacts with the server using AJAX for data retrieval and client-side interactions."
"Test Driver": "Facilitates automated regression testing and handles transmission of test data in JSON format. It performs Java testing using TestNG and JavaScript unit-testing with Jest. It also sets up a simulated web server for servlet-level tests and automates end-to-end testing using Selenium Java."
"Logic": "Manages the business logic of TEAMMATES, including handling relationships between entities, managing transactions, input value sanitization, access control rights, and interfacing with GAE-provided or third-party APIs."
"Storage": "Performs CRUD operations on data entities, validation of data, and abstraction of GQL queries, hiding the complexities of datastore from the Logic component."
"Common": "Contains utility classes, custom exceptions, and data transfer objects used across the entire application for easy consolidation and transfer of structured data."
"E2E": "Handles end-to-end testing and load & performance testing, providing helpers, abstractions of browser pages, and test cases for E2E tests and L&P tests."
"Client": "Contains scripts for administrative tasks, such as migrating data to a new schema and calculating statistics. This module connects directly to the application back-end for administrative purposes."
    }

    Code: package teammates.ui.webapi; /** * Action: joins a course for a student/instructor. */ class JoinCourseAction extends Action { private static final Logger log = Logger.getLogger(); @Override AuthType getMinAuthLevel() { return AuthType.LOGGED_IN; } @Override void checkSpecificAccessControl() { // Any user can use a join link as long as its parameters are valid } @Override public JsonResult execute() throws InvalidOperationException { String regKey = getNonNullRequestParamValue(Const.ParamsNames.REGKEY); String entityType = getNonNullRequestParamValue(Const.ParamsNames.ENTITY_TYPE); switch (entityType) { case Const.EntityType.STUDENT: return joinCourseForStudent(regKey); case Const.EntityType.INSTRUCTOR: return joinCourseForInstructor(regKey); default: throw new InvalidHttpParameterException("Error: invalid entity type"); } } private JsonResult joinCourseForStudent(String regkey) throws InvalidOperationException { StudentAttributes student; try { student = logic.joinCourseForStudent(regkey, userInfo.id); } catch (EntityDoesNotExistException ednee) { throw new EntityNotFoundException(ednee); } catch (EntityAlreadyExistsException eaee) { throw new InvalidOperationException(eaee); } catch (InvalidParametersException ipe) { // There should not be any invalid parameter here log.severe("Unexpected error", ipe); return new JsonResult(ipe.getMessage(), HttpStatus.SC_INTERNAL_SERVER_ERROR); } sendJoinEmail(student.getCourse(), student.getName(), student.getEmail(), false); return new JsonResult("Student successfully joined course"); } private JsonResult joinCourseForInstructor(String regkey) throws InvalidOperationException { InstructorAttributes instructor; try { instructor = logic.joinCourseForInstructor(regkey, userInfo.id); } catch (EntityDoesNotExistException ednee) { throw new EntityNotFoundException(ednee); } catch (EntityAlreadyExistsException eaee) { throw new InvalidOperationException(eaee); } catch (InvalidParametersException ipe) { // There should not be any invalid parameter here log.severe("Unexpected error", ipe); return new JsonResult(ipe.getMessage(), HttpStatus.SC_INTERNAL_SERVER_ERROR); } sendJoinEmail(instructor.getCourseId(), instructor.getName(), instructor.getEmail(), true); return new JsonResult("Instructor successfully joined course"); } private void sendJoinEmail(String courseId, String userName, String userEmail, boolean isInstructor) { CourseAttributes course = logic.getCourse(courseId); EmailWrapper email = emailGenerator.generateUserCourseRegisteredEmail( userName, userEmail, userInfo.id, isInstructor, course); emailSender.sendEmail(email); } }
    
Assistant: