permissions logic in tutorial 4

[kev26]

class IsOwnerOrReadOnly(permissions.BasePermission):
    def has_object_permission(self, request, view, obj):
        if request.method in permissions.SAFE_METHODS:
            print('1')
            return True
        print('2')
        return obj.owner == request.user

I'm a new learner of REST and so I feel confused about this logic, I've tried to print the case to test and it appears this result:

1
2
2
2
2
1
[13/Jun/2022 08:30:19] "GET /snippets/1/ HTTP/1.1" 200 66477
Not Found: /snippets/1/null
[13/Jun/2022 08:30:19] "GET /snippets/1/null HTTP/1.1" 404 5074

So I want to know:

1. Why we have 6 results in this case ? how to fix this ?
2. Why appear ulr GET /snippets/1/null ?
   Sorry for the bad English and thank so much for anyone help me :D

[kev26]

class UserViewSet(viewsets.ModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer
    permission_classes = [permissions.IsAuthenticated ,IsOwnerOrReadOnly]

class ApartmentViewset(viewsets.ModelViewSet):
    queryset = Apartment.objects.all()
    serializer_class = ApartmentSerializer

class TransactionVewset(viewsets.ModelViewSet):
    queryset = Transaction.objects.all()
    serializer_class = TransactionSerializer