使用SimpleRouter的ViewSet出现Django错误

from rest_framework import routers
from .views import MyViewSet

router = routers.SimpleRouter()
router.register(r'myviewset', MyViewSet)

urlpatterns = router.urls

from rest_framework import viewsets
from .models import MyModel
from .serializers import MySerializer

class MyViewSet(viewsets.ModelViewSet):
    queryset = MyModel.objects.all()
    serializer_class = MySerializer

from rest_framework import viewsets
from .models import MyModel
from .serializers import MySerializer

class MyViewSet(viewsets.ModelViewSet):
    queryset = MyModel.objects.all()
    serializer_class = MySerializer