old_contents: from django.contrib import admin
  from models import Champioship, Player, Match
  
  
  class ChampioshipAdmin(admin.ModelAdmin):
      filter_horizontal = ('players', )
  
  
  admin.site.register(Champioship, ChampioshipAdmin)
  admin.site.register(Match)
  admin.site.register(Player)
  
new_contents: from django.contrib import admin
  from models import Championship, Player, Match
  
  
  class ChampionshipAdmin(admin.ModelAdmin):
      filter_horizontal = ('players', )
  
  
  admin.site.register(Championship, ChampionshipAdmin)
  admin.site.register(Match)
  admin.site.register(Player)
  
subject: Fix allejo admin