old_contents: # -*- coding: utf-8 -*-
  #
  # Copyright 2015, Foxugly. All rights reserved.
  #
  # This program is free software: you can redistribute it and/or modify it
  # under the terms of the GNU Affero General Public License as published by
  # the Free Software Foundation, either version 3 of the License, or (at
  # your option) any later version.
  
  from django.contrib import admin
  from companies.models import Company
  
  @admin.register(Company)
  class CompanyAdmin(admin.ModelAdmin):
      filter_horizontal = ('years',)
  
  
new_contents: # -*- coding: utf-8 -*-
  #
  # Copyright 2015, Foxugly. All rights reserved.
  #
  # This program is free software: you can redistribute it and/or modify it
  # under the terms of the GNU Affero General Public License as published by
  # the Free Software Foundation, either version 3 of the License, or (at
  # your option) any later version.
  
  from django.contrib import admin
  from companies.models import Company, ModelTrimester
  
  
  @admin.register(Company)
  class CompanyAdmin(admin.ModelAdmin):
      filter_horizontal = ('years',)
  
  
  @admin.register(ModelTrimester)
  class ModelTrimesterAdmin(admin.ModelAdmin):
      filter_horizontal = ('categories',)
  
  
subject: add functionnalities