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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 get_queryset(self):
 """ Return the `QuerySet` that will be used to look up the object. Note that this method is called by the default implementation of `get_object` and may not be called if `get_object` is overridden. """

        if self.queryset is None:
            if self.model:
                return self.model._default_manager.all()
            else:
                raise ImproperlyConfigured(
                    "%(cls)s is missing a QuerySet. Define "
                    "%(cls)s.model, %(cls)s.queryset, or override "
                    "%(cls)s.get_queryset()." % {
                        'cls': self.__class__.__name__
                    }
                )
        return self.queryset.all()