using Arg = std::variant<std::monostate,
                         bool,
                         int64_t,
                         double,
                         std::string,
                         std::vector<std::string>,
                         std::ostream*>;

using Func = std::function<std::variant<std::monostate,
                 std::shared_ptr<rapidjson::Document>,
                 std::shared_ptr<arrow::RecordBatch>>()>;

using Result = std::variant<std::shared_ptr<rapidjson::Document>, Func>;

Liberator liberator;

auto table = liberator.get_table(liberator.query({
    {"symbols", std::vector<std::string>{"AAPL", "GOOGL"}},
    {"name", "daily_bars"s},
}));

(void)arrow::PrettyPrint(*table, arrow::PrettyPrintOptions(0, 1), &std::cout);

Liberator liberator;
Liberator::Result ptr;

ptr = liberator.query({
    {"symbols", std::vector<std::string>{"AAPL", "GOOGL"}},
    {"name", "daily_bars"s}
});

auto generator = *std::get_if<Liberator::Func>(&ptr);

for (auto res = generator(); res.index(); res = generator())
{
    auto batch = *std::get_if<2>(&res);
    (void)arrow::PrettyPrint(*batch, arrow::PrettyPrintOptions(0, 1),
        &std::cout);
}