old_contents: from rest_framework import serializers
  
  from sigma_core.models.group import Group
  
  
  class GroupSerializer(serializers.ModelSerializer):
      class Meta:
          model = Group
  
new_contents: from rest_framework import serializers
  
  from sigma_core.models.group import Group
  
  
  class GroupSerializer(serializers.ModelSerializer):
      class Meta:
          model = Group
      
      visibility = serializers.SerializerMethodField()
      membership_policy = serializers.SerializerMethodField()
      validation_policy = serializers.SerializerMethodField()
      type = serializers.SerializerMethodField()
  
      def get_visibility(self, obj):
          return obj.get_visibility_display()
  
      def get_membership_policy(self, obj):
          return obj.get_membership_policy_display()
  
      def get_validation_policy(self, obj):
          return obj.get_validation_policy_display()
  
      def get_type(self, obj):
          return obj.get_type_display()
  
subject: Change GroupSerializer to display attributes as strings