Users want to get rounding mode in `quantileExact` equivalent to "median_low" from Python:
https://docs.python.org/3/library/statistics.html#statistics.median_low
while current implementation works equivalent to "median_high" (?)
{
        
        if (!isNaN(x))
            array.push_back(x);
    }
    template <typename Weight>
    void add(const Value &, const Weight &)
    {
        throw Exception("Method add with weight is not implemented for QuantileExact", ErrorCodes::NOT_IMPLEMENTED);
    }
    void merge(const QuantileExact & rhs)
    {
        array.insert(rhs.array.begin(), rhs.array.end());
    }
    void serialize(WriteBuffer & buf) const