old_contents: from django.db import models
  
  
  __all__ = ['VisibilityManager', 'VisibilityManagerMixin']
  
  
  class VisibilityManagerMixin(object):
      """
      This manager should be used with a model that implements the Hideable
      mixin.
      """
  
      def __init__(self, *args, **kwargs):
          self.visible = kwargs['visible']
          super(VisibilityManagerMixin, self).__init__(*args, **kwargs)
  
      def get_queryset(self):
          return super().get_queryset()
              .filter(hidden__isnull=self.visible)
  
  
  class VisibilityManager(VisibilityManagerMixin, models.Manager):
      pass
  
new_contents: from django.db import models
  
  
  __all__ = ['VisibilityManager', 'VisibilityManagerMixin']
  
  
  class VisibilityManagerMixin(object):
      """
      This manager should be used with a model that implements the Hideable
      mixin.
      """
  
      def __init__(self, *args, **kwargs):
          self.visible = kwargs['visible']
          super(VisibilityManagerMixin, self).__init__(*args, **kwargs)
  
      def get_queryset(self):
          return super().get_queryset().filter(hidden__isnull=self.visible)
  
  
  class VisibilityManager(VisibilityManagerMixin, models.Manager):
      pass
  
subject: Correct syntax error