docs: def list_courses(args):
      """
      List enrolled courses.
  
      @param args: Command-line arguments.
      @type args: namedtuple
      """
      session = get_session()
      login(session, args.username, args.password)
      extractor = CourseraExtractor(session)
      courses = extractor.list_courses()
      logging.info('Found %d courses', len(courses))
      for course in courses:
          logging.info(course)