什么是断言？应用场景？

“`”

assert 是的作用？断言
条件成立（布尔值为True）则继续往下，否则跑出异常，一般用于：满足某个条件之后，才能执行，否则应该跑出异常。

写API的时候，继承GenericAPIView

class GenericAPIView(views.APIView):
                    """"""
                    Base class for all other generic views.
                    """"""
                    # You'll need to either set these attributes,
                    # or override `get_queryset()`/`get_serializer_class()`.
                    # If you are overriding a view method, it is important that you call
                    # `get_queryset()` instead of accessing the `queryset` property directly,
                    # as `queryset` will get evaluated only once, and those results are cached
                    # for all subsequent requests.
                    queryset = None
                    serializer_class = None

                    # If you want to use object lookups other than pk, set 'lookup_field'.
                    # For more complex lookup requirements override `get_object()`.
                    lookup_field = 'pk'
                    lookup_url_kwarg = None

                    # The filter backend classes to use for queryset filtering
                    filter_backends = api_settings.DEFAULT_FILTER_BACKENDS

                    # The style to use for queryset pagination.
                    pagination_class = api_settings.DEFAULT_PAGINATION_CLASS

                    def get_queryset(self):

                        assert self.queryset is not None, (
                            ""'%s' should either include a `queryset` attribute, ""
                            ""or override the `get_queryset()` method.""
                            % self.__class__.__name__
                        )

                        queryset = self.queryset
                        if isinstance(queryset, QuerySet):
                            # Ensure queryset is re-evaluated on each request.
                            queryset = queryset.all(
                        return queryset

            "```