new_contents: from rest_framework import generics, mixins
  
  
  from .mixins import UpdateModelMixin
  
  
  class RetrieveUpdateAPIView(mixins.RetrieveModelMixin,
                              UpdateModelMixin,
                              generics.GenericAPIView):
      """
      Concrete view for retrieving, updating a model instance.
      """
      def get(self, request, *args, **kwargs):
          return self.retrieve(request, *args, **kwargs)
  
      def put(self, request, *args, **kwargs):
          return self.update(request, *args, **kwargs)
  
      def patch(self, request, *args, **kwargs):
          return self.partial_update(request, *args, **kwargs)
  
subject: Add custom generics RetrieveUpdateAPIView