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" (?)
{
        size_t size = array.size();
        writeVarUInt(size, buf);
        buf.write(reinterpret_cast<const char *>(array.data()), size * sizeof(array[0]));
    }
    void deserialize(ReadBuffer & buf)
    {
        size_t size = 0;
        readVarUInt(size, buf);
        array.resize(size);
        buf.read(reinterpret_cast<char *>(array.data()), size * sizeof(array[0]));
    }
    
    Value get(Float64 level)
    {
        if (!array.empty())
        {
            size_t n = level < 1
                ? level * array.size()
                : (array.size() - 1);
            std::nth_element(array.begin(), array.begin() + n, array.end());    
            return array[n];
        }
        return std::numeric_limits<Value>::quiet_NaN();
    }
    
    
    void getMany(const Float64 * levels, const size_t * indices, size_t size, Value * result)