Don't require the `--structure` argument.
{
        nested_model->updateSeed();
    }
    void serialize(WriteBuffer & out) const override
    {
        nested_model->serialize(out);
    }
    void deserialize(ReadBuffer & in) override
    {
        nested_model->deserialize(in);
    }
};
class NullableModel : public IModel
{
private:
    ModelPtr nested_model;
public:
    explicit NullableModel(ModelPtr nested_model_) : nested_model(std::move(nested_model_)) {}
    void train(const IColumn & column) override
    {
        const ColumnNullable & column_nullable = assert_cast<const ColumnNullable &>(column);
        const IColumn & nested_column = column_nullable.getNestedColumn();
        nested_model->train(nested_column);
    }
    void finalize() override