old_contents: from django.contrib import admin
  
  # Register your models here.
  from .models import (
      Course, Announcement, Comment, Enrollment, Lesson, Material
  )
  
  
  class CourseAdmin(admin.ModelAdmin):
      list_display = ['name', 'slug', 'start_date', 'created_at']
      search_fields = ['name', 'slug']
      prepopulated_fields = {'slug': ['name']}
  
  
  class MaterialInlineAdmin(admin.StackedInline):
  
      model = Material
  
  
  class LessonAdmin(admin.ModelAdmin):
      list_display = ['name', 'number', 'course', 'release_date']
      search_fields = ['name', 'description']
      list_filter = ['created_at']
  
      inlines = [
          MaterialInlineAdmin
      ]
  
  admin.site.register(Course, CourseAdmin)
  admin.site.register([Enrollment, Announcement, Comment, Material])
  admin.site.register(Lesson, LessonAdmin)
  
new_contents: from django.contrib import admin
  
  # Register your models here.
  from .models import (
      Course,
      CourseTRB,
      Announcement,
      Comment,
      Enrollment,
      Lesson,
      LessonTRB,
      Material,
      KnowledgeLevel,
      CategoryDimensionCognitiveProcess,
      Verb,
  )
  
  
  class CourseAdmin(admin.ModelAdmin):
      list_display = ['name', 'slug', 'start_date', 'created_at']
      search_fields = ['name', 'slug']
      prepopulated_fields = {'slug': ['name']}
  
  
  class CourseTRBAdmin(CourseAdmin):
      pass
  
  
  class MaterialInlineAdmin(admin.StackedInline):
  
      model = Material
  
  
  class LessonAdmin(admin.ModelAdmin):
      list_display = ['name', 'number', 'course', 'release_date']
      search_fields = ['name', 'description']
      list_filter = ['created_at']
  
      inlines = [
          MaterialInlineAdmin
      ]
  
  
  admin.site.register(Course, CourseAdmin)
  admin.site.register(CourseTRB, CourseTRBAdmin)
  admin.site.register([Enrollment, Announcement, Comment, Material])
  admin.site.register(Lesson, LessonAdmin)
  admin.site.register(LessonTRB, LessonAdmin)
  admin.site.register(KnowledgeLevel)
  admin.site.register(CategoryDimensionCognitiveProcess)
  admin.site.register(Verb)
  
subject: Add new classes in admin