old_contents: from django.conf import settings
  from multiselectfield import MultiSelectField
  
  
  class TopicField(MultiSelectField):
  
      def __init__(self, *args, **kwargs):
          kwargs['max_length'] = 254
          kwargs['max_choices'] = 2
          kwargs['default'] = ''
          kwargs['blank'] = True
          super().__init__(*args, **kwargs)
  
      def contribute_to_class(self, cls, name, **kwargs):
          """
          Initialize the choices from the project's settings if they exist.
          """
          if hasattr(settings, 'A4_PROJECT_TOPICS'):
              self.choices = settings.A4_PROJECT_TOPICS
  
          # Call the super method at last so that choices are already initialized
          super().contribute_to_class(cls, name, **kwargs)
  
new_contents: from django.conf import settings
  from multiselectfield import MultiSelectField
  
  
  class TopicField(MultiSelectField):
  
      def __init__(self, *args, **kwargs):
          kwargs['max_length'] = 254
          kwargs['max_choices'] = 2
          kwargs['default'] = ''
          kwargs['blank'] = False
          super().__init__(*args, **kwargs)
  
      def contribute_to_class(self, cls, name, **kwargs):
          """
          Initialize the choices from the project's settings if they exist.
          """
          if hasattr(settings, 'A4_PROJECT_TOPICS'):
              self.choices = settings.A4_PROJECT_TOPICS
  
          # Call the super method at last so that choices are already initialized
          super().contribute_to_class(cls, name, **kwargs)
  
subject: make topics required