old_contents: # -*- coding: utf-8 -*-
  
  from __future__ import absolute_import, unicode_literals
  
  from django.db.models.manager import Manager
  
  from .query import HorizontalQuerySet
  
  
  class HorizontalManager(Manager.from_queryset(HorizontalQuerySet)):
      use_for_related_fields = True
      use_in_migrations = True
      silence_use_for_related_fields_deprecation = True  # For Django<1.10
  
      _queryset_class = HorizontalQuerySet
  
      def __init__(self):
          super(HorizontalManager, self).__init__()
          self.name = 'horizontal'
  
new_contents: # -*- coding: utf-8 -*-
  
  from __future__ import absolute_import, unicode_literals
  
  from django.db.models.manager import Manager
  
  from .query import HorizontalQuerySet
  
  
  class HorizontalManager(Manager.from_queryset(HorizontalQuerySet)):
      use_for_related_fields = True
      use_in_migrations = True
      silence_use_for_related_fields_deprecation = True  # For Django<1.10
  
      def __init__(self):
          super(HorizontalManager, self).__init__()
          self.name = 'horizontal'
  
subject: Set _queryset_class via from_queryset