Don't require the `--structure` argument.
{
private:
    UInt64 seed;
    UInt32 src_prev_value = 0;
    UInt32 res_prev_value = 0;
    const DateLUTImpl & date_lut;
public:
    explicit DateTimeModel(UInt64 seed_) : seed(seed_), date_lut(DateLUT::instance()) {}