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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def partial_update(self, request, *args, **kwargs):
 """ We do not include the mixin as we want only PATCH and no PUT """

    instance = self.get_object()
    serializer = self.get_serializer(instance, data=request.data, partial=True, context=self.get_serializer_context())
    serializer.is_valid(raise_exception=True)
    serializer.save()

    if getattr(instance, '_prefetched_objects_cache', None): #pragma: no cover
      instance = self.get_object()
      serializer = self.get_serializer(instance)

    return response.Response(serializer.data)