Merge pull request #26567 from edx/usamasadiq/bom-2363-pyupgrade

lms/djangoapps/mailing/management/commands/mailchimp_id.py

...apps/mailing/management/commands/mailchimp_sync_course.py

lms/djangoapps/mobile_api/admin.py

lms/djangoapps/mobile_api/course_info/tests.py

lms/djangoapps/mobile_api/course_info/urls.py

lms/djangoapps/mobile_api/course_info/views.py

lms/djangoapps/mobile_api/middleware.py

lms/djangoapps/mobile_api/migrations/0001_initial.py

...angoapps/mobile_api/migrations/0002_auto_20160406_0904.py

...obile_api/migrations/0003_ignore_mobile_available_flag.py

lms/djangoapps/mobile_api/mobile_platform.py

lms/djangoapps/mobile_api/models.py

lms/djangoapps/mobile_api/tests/test_decorator.py

lms/djangoapps/mobile_api/tests/test_middleware.py

lms/djangoapps/mobile_api/tests/test_milestones.py

lms/djangoapps/mobile_api/tests/test_model.py

lms/djangoapps/mobile_api/testutils.py

lms/djangoapps/mobile_api/users/serializers.py

lms/djangoapps/mobile_api/users/tests.py

lms/djangoapps/mobile_api/users/urls.py