new_contents: from django.contrib.auth import get_user_model
  
  from referrals.models import Referral
  
  from rest_framework import serializers
  
  
  class UserSerializer(serializers.ModelSerializer):
  
      class Meta:
          model = get_user_model()
          fields = ('id', 'username', 'email',)
  
  
  class ReferralSerializer(serializers.ModelSerializer):
  
      user = UserSerializer(read_only=True)
  
      class Meta:
          model = Referral
  
  
  
  
subject: add serializers