Merge pull request #9488 from edx/dsjen/courses-via-overview

Optimize OpenID Course Claims for users.

common/djangoapps/student/tests/tests.py

@@ -488,21 +488,18 @@ class DashboardTest(ModuleStoreTestCase):
         self.assertContains(response, expected_url)
 
     @unittest.skipUnless(settings.ROOT_URLCONF == 'lms.urls', 'Test only valid in lms')
-    @ddt.data((ModuleStoreEnum.Type.mongo, 1), (ModuleStoreEnum.Type.split, 3))
-    @ddt.unpack
-    def test_dashboard_metadata_caching(self, modulestore_type, expected_mongo_calls):
+    @ddt.data(ModuleStoreEnum.Type.mongo, ModuleStoreEnum.Type.split)
+    def test_dashboard_metadata_caching(self, modulestore_type):
         """
         Check that the student dashboard makes use of course metadata caching.
 
-        After enrolling a student in a course, that course's metadata should be
-        cached as a CourseOverview. The student dashboard should never have to make
-        calls to the modulestore.
+        After creating a course, that course's metadata should be cached as a
+        CourseOverview. The student dashboard should never have to make calls to
+        the modulestore.
 
         Arguments:
             modulestore_type (ModuleStoreEnum.Type): Type of modulestore to create
                 test course in.
-            expected_mongo_calls (int >=0): Number of MongoDB queries expected for
-                a single call to the module store.
 
         Note to future developers:
             If you break this test so that the "check_mongo_calls(0)" fails,
@@ -512,11 +509,11 @@ class DashboardTest(ModuleStoreTestCase):
             CourseDescriptor isn't necessary.
         """
         # Create a course and log in the user.
-        test_course = CourseFactory.create(default_store=modulestore_type)
+        # Creating a new course will trigger a publish event and the course will be cached
+        test_course = CourseFactory.create(default_store=modulestore_type, emit_signals=True)
         self.client.login(username="jack", password="test")
 
-        # Enrolling the user in the course will result in a modulestore query.
-        with check_mongo_calls(expected_mongo_calls):
+        with check_mongo_calls(0):
             CourseEnrollment.enroll(self.user, test_course.id)
 
         # Subsequent requests will only result in SQL queries to load the

common/lib/xmodule/xmodule/modulestore/tests/factories.py

@@ -114,7 +114,7 @@ class CourseFactory(XModuleFactory):
         name = kwargs.get('name', kwargs.get('run', Location.clean(kwargs.get('display_name'))))
         run = kwargs.pop('run', name)
         user_id = kwargs.pop('user_id', ModuleStoreEnum.UserID.test)
-        emit_signals = kwargs.get('emit_signals', False)
+        emit_signals = kwargs.pop('emit_signals', False)
 
         # Pass the metadata just as field=value pairs
         kwargs.update(kwargs.pop('metadata', {}))

lms/djangoapps/ccx/tests/test_tasks.py

@@ -94,17 +94,14 @@ class TestSendCCXCoursePublished(ModuleStoreTestCase):
             structure = CourseStructure.objects.get(course_id=course_key)
             self.assertEqual(structure.structure, ccx_structure)
 
-    def test_course_overview_deleted(self):
-        """Check that course overview is deleted after course published signal is sent
+    def test_course_overview_cached(self):
+        """Check that course overview is cached after course published signal is sent
         """
         course_key = CCXLocator.from_course_locator(self.course.id, self.ccx.id)
-        overview = CourseOverview(id=course_key)
-        overview.version = 1
-        overview.save()
         overview = CourseOverview.objects.filter(id=course_key)
-        self.assertEqual(len(overview), 1)
+        self.assertEqual(len(overview), 0)
         with mock_signal_receiver(SignalHandler.course_published) as receiver:
             self.call_fut(self.course.id)
             self.assertEqual(receiver.call_count, 3)
             overview = CourseOverview.objects.filter(id=course_key)
-            self.assertEqual(len(overview), 0)
+            self.assertEqual(len(overview), 1)

lms/djangoapps/oauth2_handler/handlers.py

@@ -2,9 +2,9 @@
 
 from django.conf import settings
 from django.core.cache import cache
-from xmodule.modulestore.django import modulestore
 
 from courseware.access import has_access
+from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
 from openedx.core.djangoapps.user_api.models import UserPreference
 from student.models import anonymous_id_for_user
 from student.models import UserProfile
@@ -200,13 +200,13 @@ class CourseAccessHandler(object):
         course_ids = cache.get(key)
 
         if not course_ids:
-            courses = _get_all_courses()
+            course_keys = CourseOverview.get_all_course_keys()
 
             # Global staff have access to all courses. Filter courses for non-global staff.
             if not GlobalStaff().has_user(user):
-                courses = [course for course in courses if has_access(user, access_type, course)]
+                course_keys = [course_key for course_key in course_keys if has_access(user, access_type, course_key)]
 
-            course_ids = [unicode(course.id) for course in courses]
+            course_ids = [unicode(course_key) for course_key in course_keys]
 
             cache.set(key, course_ids, self.COURSE_CACHE_TIMEOUT)
 
@@ -234,12 +234,3 @@ class IDTokenHandler(OpenIDHandler, ProfileHandler, CourseAccessHandler, Permiss
 class UserInfoHandler(OpenIDHandler, ProfileHandler, CourseAccessHandler, PermissionsHandler):
     """ Configure the UserInfo handler for the LMS. """
     pass
-
-
-def _get_all_courses():
-    """ Utility function to list all available courses. """
-
-    ms_courses = modulestore().get_courses()
-    courses = [course for course in ms_courses if course.scope_ids.block_type == 'course']
-
-    return courses

lms/djangoapps/oauth2_handler/tests.py

@@ -2,16 +2,17 @@
 from django.core.cache import cache
 from django.test.utils import override_settings
 from lang_pref import LANGUAGE_KEY
-from opaque_keys.edx.locations import SlashSeparatedCourseKey
 
-from xmodule.modulestore.tests.django_utils import TEST_DATA_MIXED_TOY_MODULESTORE
+from xmodule.modulestore.tests.factories import (check_mongo_calls, CourseFactory)
 from student.models import anonymous_id_for_user
 from student.models import UserProfile
-from student.roles import CourseStaffRole, CourseInstructorRole
+from student.roles import (CourseInstructorRole, CourseStaffRole, GlobalStaff,
+                           OrgInstructorRole, OrgStaffRole)
 from student.tests.factories import UserFactory, UserProfileFactory
 from openedx.core.djangoapps.user_api.preferences.api import set_user_preference
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 
+
 # Will also run default tests for IDTokens and UserInfo
 from oauth2_provider.tests import IDTokenTestCase, UserInfoTestCase
 
@@ -19,14 +20,10 @@ from oauth2_provider.tests import IDTokenTestCase, UserInfoTestCase
 class BaseTestMixin(ModuleStoreTestCase):
     profile = None
 
-    MODULESTORE = TEST_DATA_MIXED_TOY_MODULESTORE
-
     def setUp(self):
         super(BaseTestMixin, self).setUp()
-
-        self.course_key = SlashSeparatedCourseKey('edX', 'toy', '2012_Fall')
+        self.course_key = CourseFactory.create(emit_signals=True).id
         self.course_id = unicode(self.course_key)
-
         self.user_factory = UserFactory
         self.set_user(self.make_user())
 
@@ -77,7 +74,8 @@ class IDTokenTest(BaseTestMixin, IDTokenTestCase):
         self.assertEqual(language, locale)
 
     def test_no_special_course_access(self):
-        scopes, claims = self.get_id_token_values('openid course_instructor course_staff')
+        with check_mongo_calls(0):
+            scopes, claims = self.get_id_token_values('openid course_instructor course_staff')
         self.assertNotIn('course_staff', scopes)
         self.assertNotIn('staff_courses', claims)
 
@@ -86,14 +84,15 @@ class IDTokenTest(BaseTestMixin, IDTokenTestCase):
 
     def test_course_staff_courses(self):
         CourseStaffRole(self.course_key).add_users(self.user)
-
-        scopes, claims = self.get_id_token_values('openid course_staff')
+        with check_mongo_calls(0):
+            scopes, claims = self.get_id_token_values('openid course_staff')
 
         self.assertIn('course_staff', scopes)
         self.assertNotIn('staff_courses', claims)  # should not return courses in id_token
 
     def test_course_instructor_courses(self):
-        CourseInstructorRole(self.course_key).add_users(self.user)
+        with check_mongo_calls(0):
+            CourseInstructorRole(self.course_key).add_users(self.user)
 
         scopes, claims = self.get_id_token_values('openid course_instructor')
 
@@ -104,6 +103,7 @@ class IDTokenTest(BaseTestMixin, IDTokenTestCase):
         CourseStaffRole(self.course_key).add_users(self.user)
 
         course_id = unicode(self.course_key)
+
         nonexistent_course_id = 'some/other/course'
 
         claims = {
@@ -113,7 +113,8 @@ class IDTokenTest(BaseTestMixin, IDTokenTestCase):
             }
         }
 
-        scopes, claims = self.get_id_token_values(scope='openid course_staff', claims=claims)
+        with check_mongo_calls(0):
+            scopes, claims = self.get_id_token_values(scope='openid course_staff', claims=claims)
 
         self.assertIn('course_staff', scopes)
         self.assertIn('staff_courses', claims)
@@ -133,6 +134,11 @@ class IDTokenTest(BaseTestMixin, IDTokenTestCase):
 
 
 class UserInfoTest(BaseTestMixin, UserInfoTestCase):
+    def setUp(self):
+        super(UserInfoTest, self).setUp()
+        # create another course in the DB that only global staff have access to
+        CourseFactory.create(emit_signals=True)
+
     def token_for_scope(self, scope):
         full_scope = 'openid %s' % scope
         self.set_access_token_scope(full_scope)
@@ -158,43 +164,64 @@ class UserInfoTest(BaseTestMixin, UserInfoTestCase):
         self.assertEqual(result.status_code, 200)
         return claims
 
-    def test_request_staff_courses_using_scope(self):
-        CourseStaffRole(self.course_key).add_users(self.user)
-        claims = self.get_with_scope('course_staff')
-
-        courses = claims['staff_courses']
+    def _assert_role_using_scope(self, scope, claim, assert_one_course=True):
+        with check_mongo_calls(0):
+            claims = self.get_with_scope(scope)
+        self.assertEqual(len(claims), 2)
+        courses = claims[claim]
         self.assertIn(self.course_id, courses)
-        self.assertEqual(len(courses), 1)
+        if assert_one_course:
+            self.assertEqual(len(courses), 1)
 
-    def test_request_instructor_courses_using_scope(self):
-        CourseInstructorRole(self.course_key).add_users(self.user)
-        claims = self.get_with_scope('course_instructor')
+    def test_request_global_staff_courses_using_scope(self):
+        GlobalStaff().add_users(self.user)
+        self._assert_role_using_scope('course_staff', 'staff_courses', assert_one_course=False)
 
-        courses = claims['instructor_courses']
-        self.assertIn(self.course_id, courses)
-        self.assertEqual(len(courses), 1)
+    def test_request_org_staff_courses_using_scope(self):
+        OrgStaffRole(self.course_key.org).add_users(self.user)
+        self._assert_role_using_scope('course_staff', 'staff_courses')
 
-    def test_request_staff_courses_with_claims(self):
+    def test_request_org_instructor_courses_using_scope(self):
+        OrgInstructorRole(self.course_key.org).add_users(self.user)
+        self._assert_role_using_scope('course_instructor', 'instructor_courses')
+
+    def test_request_staff_courses_using_scope(self):
         CourseStaffRole(self.course_key).add_users(self.user)
+        self._assert_role_using_scope('course_staff', 'staff_courses')
 
+    def test_request_instructor_courses_using_scope(self):
+        CourseInstructorRole(self.course_key).add_users(self.user)
+        self._assert_role_using_scope('course_instructor', 'instructor_courses')
+
+    def _assert_role_using_claim(self, scope, claim):
         values = [self.course_id, 'some_invalid_course']
-        claims = self.get_with_claim_value('course_staff', 'staff_courses', values)
+        with check_mongo_calls(0):
+            claims = self.get_with_claim_value(scope, claim, values)
         self.assertEqual(len(claims), 2)
 
-        courses = claims['staff_courses']
+        courses = claims[claim]
         self.assertIn(self.course_id, courses)
         self.assertEqual(len(courses), 1)
 
-    def test_request_instructor_courses_with_claims(self):
-        CourseInstructorRole(self.course_key).add_users(self.user)
+    def test_request_global_staff_courses_with_claims(self):
+        GlobalStaff().add_users(self.user)
+        self._assert_role_using_claim('course_staff', 'staff_courses')
 
-        values = ['edX/toy/TT_2012_Fall', self.course_id, 'invalid_course_id']
-        claims = self.get_with_claim_value('course_instructor', 'instructor_courses', values)
-        self.assertEqual(len(claims), 2)
+    def test_request_org_staff_courses_with_claims(self):
+        OrgStaffRole(self.course_key.org).add_users(self.user)
+        self._assert_role_using_claim('course_staff', 'staff_courses')
 
-        courses = claims['instructor_courses']
-        self.assertIn(self.course_id, courses)
-        self.assertEqual(len(courses), 1)
+    def test_request_org_instructor_courses_with_claims(self):
+        OrgInstructorRole(self.course_key.org).add_users(self.user)
+        self._assert_role_using_claim('course_instructor', 'instructor_courses')
+
+    def test_request_staff_courses_with_claims(self):
+        CourseStaffRole(self.course_key).add_users(self.user)
+        self._assert_role_using_claim('course_staff', 'staff_courses')
+
+    def test_request_instructor_courses_with_claims(self):
+        CourseInstructorRole(self.course_key).add_users(self.user)
+        self._assert_role_using_claim('course_instructor', 'instructor_courses')
 
     def test_permissions_scope(self):
         claims = self.get_with_scope('permissions')

lms/envs/test.py

@@ -269,6 +269,8 @@ OPENID_PROVIDER_TRUSTED_ROOTS = ['*']
 
 ############################## OAUTH2 Provider ################################
 FEATURES['ENABLE_OAUTH2_PROVIDER'] = True
+# don't cache courses for testing
+OIDC_COURSE_HANDLER_CACHE_TIMEOUT = 0
 
 ########################### External REST APIs #################################
 FEATURES['ENABLE_MOBILE_REST_API'] = True

openedx/core/djangoapps/content/course_overviews/management/commands/generate_course_overview.py

+"""
+Command to load course overviews.
+"""
+import logging
+from optparse import make_option
+
+from django.core.management.base import BaseCommand, CommandError
+from opaque_keys import InvalidKeyError
+from opaque_keys.edx.keys import CourseKey
+from xmodule.modulestore.django import modulestore
+
+from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
+
+
+log = logging.getLogger(__name__)
+
+
+class Command(BaseCommand):
+    """
+    Example usage:
+        $ ./manage.py lms generate_course_overview --all --settings=devstack
+        $ ./manage.py lms generate_course_overview 'edX/DemoX/Demo_Course' --settings=devstack
+    """
+    args = '<course_id course_id ...>'
+    help = 'Generates and stores course overview for one or more courses.'
+
+    option_list = BaseCommand.option_list + (
+        make_option('--all',
+                    action='store_true',
+                    default=False,
+                    help='Generate course overview for all courses.'),
+    )
+
+    def handle(self, *args, **options):
+        course_keys = []
+
+        if options['all']:
+            course_keys = [course.id for course in modulestore().get_courses()]
+        else:
+            if len(args) < 1:
+                raise CommandError('At least one course or --all must be specified.')
+            try:
+                course_keys = [CourseKey.from_string(arg) for arg in args]
+            except InvalidKeyError:
+                log.fatal('Invalid key specified.')
+
+        if not course_keys:
+            log.fatal('No courses specified.')
+
+        log.info('Generating course overview for %d courses.', len(course_keys))
+        log.debug('Generating course overview(s) for the following courses: %s', course_keys)
+
+        for course_key in course_keys:
+            try:
+                CourseOverview.get_from_id(course_key)
+            except Exception as ex:  # pylint: disable=broad-except
+                log.exception('An error occurred while generating course overview for %s: %s', unicode(
+                    course_key), ex.message)
+
+        log.info('Finished generating course overviews.')

openedx/core/djangoapps/content/course_overviews/management/commands/tests/test_generate_course_overview.py

+# pylint: disable=missing-docstring
+from django.core.management.base import CommandError
+from mock import patch
+from openedx.core.djangoapps.content.course_overviews.management.commands import generate_course_overview
+from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.modulestore.tests.factories import CourseFactory
+
+
+class TestGenerateCourseOverview(ModuleStoreTestCase):
+    """
+    Tests course overview management command.
+    """
+    def setUp(self):
+        """
+        Create courses in modulestore.
+        """
+        super(TestGenerateCourseOverview, self).setUp()
+        self.course_key_1 = CourseFactory.create().id
+        self.course_key_2 = CourseFactory.create().id
+        self.command = generate_course_overview.Command()
+
+    def _assert_courses_not_in_overview(self, *courses):
+        """
+        Assert that courses doesn't exist in the course overviews.
+        """
+        course_keys = CourseOverview.get_all_course_keys()
+        for expected_course_key in courses:
+            self.assertNotIn(expected_course_key, course_keys)
+
+    def _assert_courses_in_overview(self, *courses):
+        """
+        Assert courses exists in course overviews.
+        """
+        course_keys = CourseOverview.get_all_course_keys()
+        for expected_course_key in courses:
+            self.assertIn(expected_course_key, course_keys)
+
+    def test_generate_all(self):
+        """
+        Test that all courses in the modulestore are loaded into course overviews.
+        """
+        # ensure that the newly created courses aren't in course overviews
+        self._assert_courses_not_in_overview(self.course_key_1, self.course_key_2)
+        self.command.handle(all=True)
+
+        # CourseOverview will be populated with all courses in the modulestore
+        self._assert_courses_in_overview(self.course_key_1, self.course_key_2)
+
+    def test_generate_one(self):
+        """
+        Test that a specified course is loaded into course overviews.
+        """
+        self._assert_courses_not_in_overview(self.course_key_1, self.course_key_2)
+        self.command.handle(unicode(self.course_key_1), all=False)
+        self._assert_courses_in_overview(self.course_key_1)
+        self._assert_courses_not_in_overview(self.course_key_2)
+
+    @patch('openedx.core.djangoapps.content.course_overviews.management.commands.generate_course_overview.log')
+    def test_invalid_key(self, mock_log):
+        """
+        Test that invalid key errors are logged.
+        """
+        self.command.handle('not/found', all=False)
+        self.assertTrue(mock_log.fatal.called)
+
+    @patch('openedx.core.djangoapps.content.course_overviews.management.commands.generate_course_overview.log')
+    def test_not_found_key(self, mock_log):
+        """
+        Test keys not found are logged.
+        """
+        self.command.handle('fake/course/id', all=False)
+        self.assertTrue(mock_log.exception.called)
+
+    def test_no_params(self):
+        """
+        Test exception raised when no parameters are specified.
+        """
+        with self.assertRaises(CommandError):
+            self.command.handle(all=False)

openedx/core/djangoapps/content/course_overviews/models.py

@@ -9,6 +9,7 @@ from django.db.utils import IntegrityError
 from django.utils.translation import ugettext
 from model_utils.models import TimeStampedModel
 
+from opaque_keys.edx.keys import CourseKey
 from util.date_utils import strftime_localized
 from xmodule import course_metadata_utils
 from xmodule.course_module import CourseDescriptor
@@ -151,7 +152,7 @@ class CourseOverview(TimeStampedModel):
         )
 
     @classmethod
-    def _load_from_module_store(cls, course_id):
+    def load_from_module_store(cls, course_id):
         """
         Load a CourseDescriptor, create a new CourseOverview from it, cache the
         overview, and return it.
@@ -225,7 +226,7 @@ class CourseOverview(TimeStampedModel):
                 course_overview = None
         except cls.DoesNotExist:
             course_overview = None
-        return course_overview or cls._load_from_module_store(course_id)
+        return course_overview or cls.load_from_module_store(course_id)
 
     def clean_id(self, padding_char='='):
         """
@@ -340,3 +341,13 @@ class CourseOverview(TimeStampedModel):
         Returns a list of ID strings for this course's prerequisite courses.
         """
         return json.loads(self._pre_requisite_courses_json)
+
+    @classmethod
+    def get_all_course_keys(cls):
+        """
+        Returns all course keys from course overviews.
+        """
+        return [
+            CourseKey.from_string(course_overview['id'])
+            for course_overview in CourseOverview.objects.values('id')
+        ]

openedx/core/djangoapps/content/course_overviews/signals.py

@@ -11,9 +11,10 @@ from xmodule.modulestore.django import SignalHandler
 def _listen_for_course_publish(sender, course_key, **kwargs):  # pylint: disable=unused-argument
     """
     Catches the signal that a course has been published in Studio and
-    invalidates the corresponding CourseOverview cache entry if one exists.
+    updates the corresponding CourseOverview cache entry.
     """
     CourseOverview.objects.filter(id=course_key).delete()
+    CourseOverview.load_from_module_store(course_key)
 
 
 @receiver(SignalHandler.course_deleted)

openedx/core/djangoapps/content/course_overviews/tests.py

@@ -258,31 +258,22 @@ class CourseOverviewTestCase(ModuleStoreTestCase):
                 self.store.delete_course(course.id, ModuleStoreEnum.UserID.test)
                 CourseOverview.get_from_id(course.id)
 
-    @ddt.data((ModuleStoreEnum.Type.mongo, 1, 1), (ModuleStoreEnum.Type.split, 3, 4))
-    @ddt.unpack
-    def test_course_overview_caching(self, modulestore_type, min_mongo_calls, max_mongo_calls):
+    @ddt.data(ModuleStoreEnum.Type.mongo, ModuleStoreEnum.Type.split)
+    def test_course_overview_caching(self, modulestore_type):
         """
         Tests that CourseOverview structures are actually getting cached.
 
         Arguments:
             modulestore_type (ModuleStoreEnum.Type): type of store to create the
                 course in.
-            min_mongo_calls (int): minimum number of MongoDB queries we expect
-                to be made.
-            max_mongo_calls (int): maximum number of MongoDB queries we expect
-                to be made.
         """
-        course = CourseFactory.create(default_store=modulestore_type)
 
-        # The first time we load a CourseOverview, it will be a cache miss, so
-        # we expect the modulestore to be queried.
-        with check_mongo_calls_range(max_finds=max_mongo_calls, min_finds=min_mongo_calls):
-            _course_overview_1 = CourseOverview.get_from_id(course.id)
+        # Creating a new course will trigger a publish event and the course will be cached
+        course = CourseFactory.create(default_store=modulestore_type, emit_signals=True)
 
-        # The second time we load a CourseOverview, it will be a cache hit, so
-        # we expect no modulestore queries to be made.
+        # The cache will be hit and mongo will not be queried
         with check_mongo_calls(0):
-            _course_overview_2 = CourseOverview.get_from_id(course.id)
+            CourseOverview.get_from_id(course.id)
 
     @ddt.data(ModuleStoreEnum.Type.split, ModuleStoreEnum.Type.mongo)
     def test_get_non_existent_course(self, modulestore_type):
@@ -298,24 +289,18 @@ class CourseOverviewTestCase(ModuleStoreTestCase):
         with self.assertRaises(CourseOverview.DoesNotExist):
             CourseOverview.get_from_id(store.make_course_key('Non', 'Existent', 'Course'))
 
-    @ddt.data(ModuleStoreEnum.Type.split, ModuleStoreEnum.Type.mongo)
-    def test_get_errored_course(self, modulestore_type):
+    def test_get_errored_course(self):
         """
         Test that getting an ErrorDescriptor back from the module store causes
-        get_from_id to raise an IOError.
-
-        Arguments:
-            modulestore_type (ModuleStoreEnum.Type): type of store to create the
-                course in.
+        load_from_module_store to raise an IOError.
         """
-        course = CourseFactory.create(default_store=modulestore_type)
         mock_get_course = mock.Mock(return_value=ErrorDescriptor)
         with mock.patch('xmodule.modulestore.mixed.MixedModuleStore.get_course', mock_get_course):
             # This mock makes it so when the module store tries to load course data,
             # an exception is thrown, which causes get_course to return an ErrorDescriptor,
             # which causes get_from_id to raise an IOError.
             with self.assertRaises(IOError):
-                CourseOverview.get_from_id(course.id)
+                CourseOverview.load_from_module_store(self.store.make_course_key('Non', 'Existent', 'Course'))
 
     def test_malformed_grading_policy(self):
         """