old_contents: from django.contrib import admin
  from experiment_session.models import ExperimentSession, Combination
  
  # Register your models here.
  admin.site.register(ExperimentSession)
  admin.site.register(Combination)
  
new_contents: from django.contrib import admin
  from experiment_session.models import ExperimentSession, Combination, Repeat
  
  # Register your models here.
  admin.site.register(ExperimentSession)
  admin.site.register(Combination)
  admin.site.register(Repeat)
  
subject: Add Repeats model to admin