old_contents: from django.contrib.auth import get_user_model
  
  from rest_framework import serializers
  
  
  class VoterSerializer(serializers.ModelSerializer):
      full_name = serializers.CharField(source='get_full_name', required=False)
  
      class Meta:
          model = get_user_model()
          fields = ('id', 'username', 'first_name', 'last_name', 'full_name')
  
new_contents: from rest_framework import serializers
  
  from taiga.users.models import User
  
  
  class VoterSerializer(serializers.ModelSerializer):
      full_name = serializers.CharField(source='get_full_name', required=False)
  
      class Meta:
          model = User
          fields = ('id', 'username', 'first_name', 'last_name', 'full_name')
  
subject: Fix import