old_contents: from django.contrib import admin
  
  from .models import TalkProposal, TutorialProposal
  
  
  admin.site.register(TalkProposal)
  admin.site.register(TutorialProposal)
  
new_contents: from django.contrib import admin
  
  from .models import TalkProposal, PosterProposal, TutorialProposal
  
  
  admin.site.register(TalkProposal)
  admin.site.register(PosterProposal)
  admin.site.register(TutorialProposal)
  
subject: add poster proposals in the admin interface