old_contents: from django.db import IntegrityError
  
  from rest_framework.permissions import IsAuthenticated
  from rest_framework.views import APIView
  from rest_framework.response import Response
  from rest_framework import status
  
  from .serializers import DeviceSerializer
  
  
  class DeviceTokenSetter(APIView):
      """
      Set a push token related to device for logged in User
      """
      permission_classes = (IsAuthenticated, )
  
      def post(self, request, format=None):
          serializer = DeviceSerializer(data=request.data)
          if serializer.is_valid(raise_exception=True):
              try:
                  serializer.save(user=request.user)
                  return Response(status=status.HTTP_201_CREATED)
              except IntegrityError:
                  return Response('Device instance already exists.', status=status.HTTP_409_CONFLICT)
  
new_contents: from django.db import IntegrityError
  
  from rest_framework.permissions import IsAuthenticated
  from rest_framework.views import APIView
  from rest_framework.response import Response
  from rest_framework import status
  
  from .serializers import DeviceSerializer
  
  
  class DeviceTokenSetter(APIView):
      """
      Set a push token related to device for logged in User
      """
      permission_classes = (IsAuthenticated, )
  
      def post(self, request, format=None):
          serializer = DeviceSerializer(data=request.data)
          if serializer.is_valid(raise_exception=True):
              try:
                  serializer.save(user=request.user)
                  return Response(status=status.HTTP_201_CREATED)
              except IntegrityError:
                  return Response('Device instance already exists.', status=status.HTTP_200_OK)
  
subject: Return status code 200 when Device instance already exists