new_contents: from django.contrib import admin
  from .models import Rate, RateSource
  
  
  class RateInline(admin.TabularInline):
      model = Rate
  
  
  class RateSourceAdmin(admin.ModelAdmin):
      inlines = [
          RateInline,
      ]
  
  
  admin.site.register(RateSource, RateSourceAdmin)
  
subject: Add models to admin